electron/patches/chromium/mas_avoid_private_macos_api_usage.patch.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Samuel Attard <samuel.r.attard@gmail.com>
Date: Thu, 20 Sep 2018 17:48:49 -0700
Subject: mas: avoid private macOS API usage

* Use the stub killring file when building blink
* Remove usage of the following private APIs
  * abort_report_np
  * pthread_fchdir_np
  * pthread_chdir_np
  * SetApplicationIsDaemon
  * _LSSetApplicationLaunchServicesServerConnectionStatus
  * AreDeviceAndUserJoinedToDomain
  * _CFIsObjC
  * AudioDeviceDuck
  * NSNextStepFrame
  * NSThemeFrame
  * NSTextInputReplacementRangeAttributeName
* NSAccessibilityRemoteUIElement is unnecessary for Electron's use-case. We use it
for progressive web apps (where the AXTree is in the browser process, but macOS
needs to think it's coming from the PWA process). I think it can just be chopped
out -- if there are any side-effects, we should be able to work around them.
* CAContext removal
  * For apps that spend a lot of time watching video (especially fullscreen video),
    the power/battery usage will likely increase 1.5x to 2x. For something that is,
    e.g, scrolling, it'll be smaller, more like 1.15x or 1.25x.

    In terms of performance, the impact will likely be fairly small -- any app that
    could hit 60fps before will likely still be able to hit 60fps. There may even be
    cases where performance improves when disabling remote CoreAnimation (remote
    CoreAnimation is really only about battery usage).
* CTFontDescriptorIsSystemUIFont is a private API, we're using an
_interesting_ technique in the MAS build to determine if the font is a
system font by checking if it's kCTFontPriorityAttribute is set to
system priority.

diff --git a/base/BUILD.gn b/base/BUILD.gn
index 2a127468d8fcb1d24c2e05ce0e54528386686dff..430ceff387516f71fac947017df1e45e4929f164 100644
--- a/base/BUILD.gn
+++ b/base/BUILD.gn
@@ -1069,6 +1069,7 @@ component("base") {
     "//build:ios_buildflags",
     "//build/config/compiler:compiler_buildflags",
     "//third_party/modp_b64",
+    "//electron/build/config:generate_mas_config",
   ]
 
   # Used by metrics/crc32
diff --git a/base/enterprise_util_mac.mm b/base/enterprise_util_mac.mm
index 4bf9a3c27e05c6635b2beb8e880b5b43dbed61b5..f328fbb49c45991f44a9c75325491d0873746b61 100644
--- a/base/enterprise_util_mac.mm
+++ b/base/enterprise_util_mac.mm
@@ -16,6 +16,7 @@
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
 #include "base/strings/sys_string_conversions.h"
+#include "electron/mas.h"
 
 namespace base {
 
@@ -116,6 +117,14 @@ DeviceUserDomainJoinState AreDeviceAndUserJoinedToDomain() {
     DeviceUserDomainJoinState state{.device_joined = false,
                                     .user_joined = false};
 
+#if IS_MAS_BUILD()
+    return state;
+  }();
+
+  return state;
+}
+#else
+
     @autoreleasepool {
       ODSession* session = [ODSession defaultSession];
       if (session == nil) {
@@ -219,5 +228,6 @@ DeviceUserDomainJoinState AreDeviceAndUserJoinedToDomain() {
 
   return state;
 }
+#endif
 
 }  // namespace base
diff --git a/base/process/launch_mac.cc b/base/process/launch_mac.cc
index b63d58da9837ba4d1e4aff8f24f2cd977c5ed02d..8387fd7d2bcf8951b6cc024829c16d970799190c 100644
--- a/base/process/launch_mac.cc
+++ b/base/process/launch_mac.cc
@@ -84,6 +84,10 @@ int posix_spawnattr_set_csm_np(const posix_spawnattr_t*, uint32_t)
 #include "base/threading/scoped_blocking_call.h"
 #include "base/threading/thread_restrictions.h"
 #include "base/trace_event/trace_event.h"
+#include "electron/mas.h"
+#if IS_MAS_BUILD()
+#include <sys/syscall.h>
+#endif
 
 #if BUILDFLAG(IS_MAC)
 #include "base/apple/mach_port_rendezvous_mac.h"
@@ -92,9 +96,11 @@ int posix_spawnattr_set_csm_np(const posix_spawnattr_t*, uint32_t)
 extern "C" {
 // Changes the current thread's directory to a path or directory file
 // descriptor.
+#if !IS_MAS_BUILD()
 int pthread_chdir_np(const char* dir);
 
 int pthread_fchdir_np(int fd);
+#endif
 
 int responsibility_spawnattrs_setdisclaim(posix_spawnattr_t attrs,
                                           int disclaim);
@@ -171,13 +177,27 @@ class PosixSpawnFileActions {
 
 #if !BUILDFLAG(IS_MAC)
 int ChangeCurrentThreadDirectory(const char* path) {
+#if IS_MAS_BUILD()
+  #pragma clang diagnostic push
+  #pragma clang diagnostic ignored "-Wdeprecated-declarations"
+  return syscall(SYS___pthread_chdir, path);
+  #pragma clang diagnostic pop
+#else
   return pthread_chdir_np(path);
+#endif
 }
 
 // The recommended way to unset a per-thread cwd is to set a new value to an
 // invalid file descriptor, per libpthread-218.1.3/private/private.h.
 int ResetCurrentThreadDirectory() {
+#if IS_MAS_BUILD()
+  #pragma clang diagnostic push
+  #pragma clang diagnostic ignored "-Wdeprecated-declarations"
+  return syscall(SYS___pthread_fchdir, -1);
+  #pragma clang diagnostic pop
+#else
   return pthread_fchdir_np(-1);
+#endif
 }
 #endif
 
@@ -301,7 +321,7 @@ Process LaunchProcess(const std::vector<std::string>& argv,
     file_actions.Inherit(STDERR_FILENO);
   }
 
-#if BUILDFLAG(IS_MAC)
+#if 0
   if (options.disclaim_responsibility) {
     DPSXCHECK(responsibility_spawnattrs_setdisclaim(attr.get(), 1));
   }
diff --git a/base/process/process_info_mac.mm b/base/process/process_info_mac.mm
index e12c1d078147d956a1d9b1bc498c1b1d6fe7b974..233362259dc4e728ed37435e650417647b45a6af 100644
--- a/base/process/process_info_mac.mm
+++ b/base/process/process_info_mac.mm
@@ -4,15 +4,20 @@
 
 #include "base/process/process_info.h"
 
+#include "electron/mas.h"
+
 #import <AppKit/AppKit.h>
 #include <unistd.h>
 
+#if !IS_MAS_BUILD()
 extern "C" {
 pid_t responsibility_get_pid_responsible_for_pid(pid_t);
 }
+#endif
 
 namespace {
 
+#if !IS_MAS_BUILD()
 bool AppContainsBluetoothUsageDescription(NSRunningApplication* app) {
   NSURL* bundle_url = app.bundleURL;
   if (!bundle_url) {
@@ -24,12 +29,14 @@ bool AppContainsBluetoothUsageDescription(NSRunningApplication* app) {
       [bundle objectForInfoDictionaryKey:@"NSBluetoothAlwaysUsageDescription"];
   return bluetooth_entry != nil;
 }
+#endif
 
 }  // namespace
 
 namespace base {
 
 bool DoesResponsibleProcessHaveBluetoothMetadata() {
+#if !IS_MAS_BUILD()
   const pid_t pid = getpid();
   const pid_t responsible_pid = responsibility_get_pid_responsible_for_pid(pid);
   // Returns true directly if this is a self-responsible app(e.g. Chrome opens
@@ -46,6 +53,9 @@ bool DoesResponsibleProcessHaveBluetoothMetadata() {
     return AppContainsBluetoothUsageDescription(app);
   }
   return false;
+#else
+  return true;
+#endif
 }
 
 }  // namespace base
diff --git a/components/os_crypt/common/keychain_password_mac.mm b/components/os_crypt/common/keychain_password_mac.mm
index caa0e420956a31be1bd744319a0e40a0e50b46cf..f19628cc0cdba39b232f55935e8eee9786b02a77 100644
--- a/components/os_crypt/common/keychain_password_mac.mm
+++ b/components/os_crypt/common/keychain_password_mac.mm
@@ -16,6 +16,7 @@
 #include "base/strings/string_view_util.h"
 #include "build/branding_buildflags.h"
 #include "crypto/apple/keychain.h"
+#include "electron/mas.h"
 #include "third_party/abseil-cpp/absl/cleanup/cleanup.h"
 
 using crypto::apple::Keychain;
diff --git a/components/os_crypt/sync/BUILD.gn b/components/os_crypt/sync/BUILD.gn
index 2d155f49248a24b5551cb93e010ac1a0c0f94261..23aa391aaf380f87310fb295277809f8b105d6e8 100644
--- a/components/os_crypt/sync/BUILD.gn
+++ b/components/os_crypt/sync/BUILD.gn
@@ -61,6 +61,7 @@ component("sync") {
     deps += [
       "//components/os_crypt/common:keychain_password_mac",
       "//crypto:mock_apple_keychain",
+      "//electron/build/config:generate_mas_config"
     ]
   } else if (is_win) {
     sources += [ "os_crypt_win.cc" ]
diff --git a/components/remote_cocoa/app_shim/BUILD.gn b/components/remote_cocoa/app_shim/BUILD.gn
index ba813851fde2660c21f99248a124161d2ac2ca07..c34f920e4a592b6798f5307c726bc34ebedf3f88 100644
--- a/components/remote_cocoa/app_shim/BUILD.gn
+++ b/components/remote_cocoa/app_shim/BUILD.gn
@@ -77,6 +77,7 @@ component("app_shim") {
     "//components/crash/core/common",
     "//components/remote_cocoa/common:mojo",
     "//components/system_media_controls",
+    "//electron/build/config:generate_mas_config",
     "//mojo/public/cpp/bindings",
     "//net",
     "//ui/accelerated_widget_mac",
diff --git a/components/remote_cocoa/app_shim/application_bridge.mm b/components/remote_cocoa/app_shim/application_bridge.mm
index b5801f8d4b4d5f5ed9f70b61cbd63f28a80840a6..7bf371952ba5ce01f28c79ffe156ee33812d6874 100644
--- a/components/remote_cocoa/app_shim/application_bridge.mm
+++ b/components/remote_cocoa/app_shim/application_bridge.mm
@@ -12,6 +12,7 @@
 #include "components/remote_cocoa/app_shim/native_widget_ns_window_bridge.h"
 #include "components/remote_cocoa/app_shim/native_widget_ns_window_host_helper.h"
 #include "components/system_media_controls/mac/remote_cocoa/system_media_controls_bridge.h"
+#include "electron/mas.h"
 #include "mojo/public/cpp/bindings/associated_remote.h"
 #include "mojo/public/cpp/bindings/self_owned_receiver.h"
 #include "ui/accelerated_widget_mac/window_resize_helper_mac.h"
@@ -51,6 +52,7 @@
 
   // NativeWidgetNSWindowHostHelper:
   id GetNativeViewAccessible() override {
+#if !IS_MAS_BUILD()
     if (!remote_accessibility_element_) {
       base::ProcessId browser_pid = base::kNullProcessId;
       std::vector<uint8_t> element_token;
@@ -61,6 +63,9 @@ id GetNativeViewAccessible() override {
           ui::RemoteAccessibility::GetRemoteElementFromToken(element_token);
     }
     return remote_accessibility_element_;
+#else
+    return nil;
+#endif
   }
   void DispatchKeyEvent(ui::KeyEvent* event) override {
     bool event_handled = false;
@@ -99,7 +104,9 @@ void GetWordAt(const gfx::Point& location_in_content,
   mojo::AssociatedRemote<mojom::TextInputHost> text_input_host_remote_;
 
   std::unique_ptr<NativeWidgetNSWindowBridge> bridge_;
+#if !IS_MAS_BUILD()
   NSAccessibilityRemoteUIElement* __strong remote_accessibility_element_;
+#endif
 };
 
 bool g_is_out_of_process_app_shim = false;
diff --git a/components/remote_cocoa/app_shim/browser_native_widget_window_mac.mm b/components/remote_cocoa/app_shim/browser_native_widget_window_mac.mm
index f7200edbe6059ac6d7ade0672852b52da7642a71..0cc5da96411b46eb39d0c01dfec59cb503df0d9b 100644
--- a/components/remote_cocoa/app_shim/browser_native_widget_window_mac.mm
+++ b/components/remote_cocoa/app_shim/browser_native_widget_window_mac.mm
@@ -9,7 +9,9 @@
 #include "base/mac/mac_util.h"
 #include "components/remote_cocoa/app_shim/native_widget_ns_window_bridge.h"
 #include "components/remote_cocoa/common/native_widget_ns_window_host.mojom.h"
+#include "electron/mas.h"
 
+#if !IS_MAS_BUILD()
 namespace {
 // Workaround for https://crbug.com/1369643
 const double kThinControllerHeight = 0.5;
@@ -125,12 +127,15 @@ - (void)maybeShowTrafficLights {
 
 @end
 
+#endif  // MAS_BUILD
+
 @implementation BrowserNativeWidgetWindow
 
 @synthesize thinTitlebarViewController = _thinTitlebarViewController;
 
 // NSWindow (PrivateAPI) overrides.
 
+#if !IS_MAS_BUILD()
 + (Class)frameViewClassForStyleMask:(NSUInteger)windowStyle {
   // - NSThemeFrame and its subclasses will be nil if it's missing at runtime.
   if ([BrowserWindowFrame class])
@@ -189,6 +194,8 @@ - (BOOL)_usesCustomDrawing {
   return NO;
 }
 
+#endif  // MAS_BUILD
+
 // Handle "Move focus to the window toolbar" configured in System Preferences ->
 // Keyboard -> Shortcuts -> Keyboard. Usually Ctrl+F5. The argument (|unknown|)
 // tends to just be nil.
@@ -199,8 +206,8 @@ - (void)_handleFocusToolbarHotKey:(id)unknown {
 }
 
 - (void)setAlwaysShowTrafficLights:(BOOL)alwaysShow {
-  [base::apple::ObjCCastStrict<BrowserWindowFrame>(self.contentView.superview)
-      setAlwaysShowTrafficLights:alwaysShow];
+  // [base::apple::ObjCCastStrict<BrowserWindowFrame>(self.contentView.superview)
+  //    setAlwaysShowTrafficLights:alwaysShow];
 }
 
 @end
diff --git a/components/remote_cocoa/app_shim/native_widget_mac_frameless_nswindow.mm b/components/remote_cocoa/app_shim/native_widget_mac_frameless_nswindow.mm
index 3a815ebf505bd95fa7f6b61ba433d98fbfe20225..149de0175c2ec0e41e3ba40caad7019ca87386d6 100644
--- a/components/remote_cocoa/app_shim/native_widget_mac_frameless_nswindow.mm
+++ b/components/remote_cocoa/app_shim/native_widget_mac_frameless_nswindow.mm
@@ -4,6 +4,10 @@
 
 #import "components/remote_cocoa/app_shim/native_widget_mac_frameless_nswindow.h"
 
+#include "electron/mas.h"
+
+#if !IS_MAS_BUILD()
+
 @interface NSWindow (PrivateAPI)
 + (Class)frameViewClassForStyleMask:(NSUInteger)windowStyle;
 @end
@@ -18,8 +22,12 @@ - (CGFloat)_titlebarHeight {
 }
 @end
 
+#endif  // MAS_BUILD
+
 @implementation NativeWidgetMacFramelessNSWindow
 
+#if !IS_MAS_BUILD()
+
 + (Class)frameViewClassForStyleMask:(NSUInteger)windowStyle {
   if ([NativeWidgetMacFramelessNSWindowFrame class]) {
     return [NativeWidgetMacFramelessNSWindowFrame class];
@@ -27,4 +35,6 @@ + (Class)frameViewClassForStyleMask:(NSUInteger)windowStyle {
   return [super frameViewClassForStyleMask:windowStyle];
 }
 
+#endif  // MAS_BUILD
+
 @end
diff --git a/components/remote_cocoa/app_shim/native_widget_mac_nswindow.h b/components/remote_cocoa/app_shim/native_widget_mac_nswindow.h
index 71158ca9a7101911bb76f0c1b5300b0ff0e326b3..1441b9d4f9560c8b26d4beffe31449ed2a1eed40 100644
--- a/components/remote_cocoa/app_shim/native_widget_mac_nswindow.h
+++ b/components/remote_cocoa/app_shim/native_widget_mac_nswindow.h
@@ -9,6 +9,7 @@
 
 #include "base/apple/foundation_util.h"
 #include "components/remote_cocoa/app_shim/remote_cocoa_app_shim_export.h"
+#include "electron/mas.h"
 #import "ui/base/cocoa/command_dispatcher.h"
 
 namespace remote_cocoa {
@@ -17,6 +18,7 @@ class NativeWidgetNSWindowBridge;
 
 @protocol WindowTouchBarDelegate;
 
+#if !IS_MAS_BUILD()
 // Weak lets Chrome launch even if a future macOS doesn't have the below classes
 WEAK_IMPORT_ATTRIBUTE
 @interface NSNextStepFrame : NSView
@@ -33,6 +35,7 @@ REMOTE_COCOA_APP_SHIM_EXPORT
 REMOTE_COCOA_APP_SHIM_EXPORT
 @interface NativeWidgetMacNSWindowTitledFrame : NSThemeFrame
 @end
+#endif
 
 // The NSWindow used by BridgedNativeWidget. Provides hooks into AppKit that
 // can only be accomplished by overriding methods.
diff --git a/components/remote_cocoa/app_shim/native_widget_mac_nswindow.mm b/components/remote_cocoa/app_shim/native_widget_mac_nswindow.mm
index 433f12928857e288b6b0d4f4dd3d1f29da08cf6c..bb95aabec2e0d5c7b3a5d315c9a3f8cb3a45c8d2 100644
--- a/components/remote_cocoa/app_shim/native_widget_mac_nswindow.mm
+++ b/components/remote_cocoa/app_shim/native_widget_mac_nswindow.mm
@@ -21,6 +21,7 @@
 #import "components/remote_cocoa/app_shim/views_nswindow_delegate.h"
 #import "components/remote_cocoa/app_shim/window_touch_bar_delegate.h"
 #include "components/remote_cocoa/common/native_widget_ns_window_host.mojom.h"
+#include "electron/mas.h"
 #include "ui/accessibility/platform/ax_platform_node.h"
 #import "ui/base/cocoa/user_interface_item_command_handler.h"
 #import "ui/base/cocoa/window_size_constants.h"
@@ -108,14 +109,18 @@ void OrderChildWindow(NSWindow* child_window,
 
 }  // namespace
 
+#if !IS_MAS_BUILD()
 @interface NSNextStepFrame (Private)
 - (instancetype)initWithFrame:(NSRect)frame
                     styleMask:(NSUInteger)styleMask
                         owner:(id)owner;
 @end
+#endif
 
 @interface NSWindow (Private)
+#if !IS_MAS_BUILD()
 + (Class)frameViewClassForStyleMask:(NSWindowStyleMask)windowStyle;
+#endif
 - (BOOL)hasKeyAppearance;
 - (long long)_resizeDirectionForMouseLocation:(CGPoint)location;
 - (BOOL)_isConsideredOpenForPersistentState;
@@ -165,6 +170,8 @@ - (void)cr_mouseDownOnFrameView:(NSEvent*)event {
 }
 @end
 
+#if !IS_MAS_BUILD()
+
 @implementation NativeWidgetMacNSWindowTitledFrame
 - (void)mouseDown:(NSEvent*)event {
   if (self.window.isMovable)
@@ -192,6 +199,8 @@ - (BOOL)usesCustomDrawing {
 }
 @end
 
+#endif  // MAS_BUILD
+
 @implementation NativeWidgetMacNSWindow {
  @private
   CommandDispatcher* __strong _commandDispatcher;
@@ -389,6 +398,8 @@ - (NSAccessibilityRole)accessibilityRole {
 
 // NSWindow overrides.
 
+#if !IS_MAS_BUILD()
+
 + (Class)frameViewClassForStyleMask:(NSWindowStyleMask)windowStyle {
   if (windowStyle & NSWindowStyleMaskTitled) {
     if (Class customFrame = [NativeWidgetMacNSWindowTitledFrame class])
@@ -400,6 +411,8 @@ + (Class)frameViewClassForStyleMask:(NSWindowStyleMask)windowStyle {
   return [super frameViewClassForStyleMask:windowStyle];
 }
 
+#endif
+
 - (BOOL)_isTitleHidden {
   bool shouldShowWindowTitle = YES;
   if (_bridge)
diff --git a/components/remote_cocoa/app_shim/native_widget_ns_window_bridge.mm b/components/remote_cocoa/app_shim/native_widget_ns_window_bridge.mm
index f3ea2bf2d15d815a2409441a9033a92d5d8967c1..ce52245628c72018da8ec4a3155dafa74e42c8e3 100644
--- a/components/remote_cocoa/app_shim/native_widget_ns_window_bridge.mm
+++ b/components/remote_cocoa/app_shim/native_widget_ns_window_bridge.mm
@@ -42,6 +42,7 @@
 #import "components/remote_cocoa/app_shim/views_nswindow_delegate.h"
 #import "components/remote_cocoa/app_shim/window_move_loop.h"
 #include "components/remote_cocoa/common/native_widget_ns_window_host.mojom.h"
+#include "electron/mas.h"
 #include "mojo/public/cpp/bindings/self_owned_receiver.h"
 #include "net/cert/x509_util_apple.h"
 #include "ui/accelerated_widget_mac/window_resize_helper_mac.h"
@@ -692,10 +693,12 @@ NSUInteger CountBridgedWindows(NSArray* child_windows) {
   // this should be treated as an error and caught early.
   CHECK(bridged_view_);
 
+#if !IS_MAS_BUILD()
   // Send the accessibility tokens for the NSView now that it exists.
   host_->SetRemoteAccessibilityTokens(
       ui::RemoteAccessibility::GetTokenForLocalElement(window_),
       ui::RemoteAccessibility::GetTokenForLocalElement(bridged_view_));
+#endif
 
   // Beware: This view was briefly removed (in favor of a bare CALayer) in
   // https://crrev.com/c/1236675. The ordering of unassociated layers relative
diff --git a/components/viz/service/BUILD.gn b/components/viz/service/BUILD.gn
index 40718df4d3d7092309ea7027ae6c59a7963fd03c..89f08e2693d9101e89dd007df80881ff726195ad 100644
--- a/components/viz/service/BUILD.gn
+++ b/components/viz/service/BUILD.gn
@@ -387,6 +387,7 @@ viz_component("service") {
         "frame_sinks/external_begin_frame_source_mac.h",
       ]
     }
+    deps += ["//electron/build/config:generate_mas_config"]
   }
 
   if (is_ios) {
@@ -710,6 +711,7 @@ viz_source_set("unit_tests") {
       "display_embedder/software_output_device_mac_unittest.mm",
     ]
     frameworks = [ "IOSurface.framework" ]
+    deps += ["//electron/build/config:generate_mas_config"]
   }
 
   if (is_win) {
diff --git a/content/app_shim_remote_cocoa/ns_view_bridge_factory_impl.mm b/content/app_shim_remote_cocoa/ns_view_bridge_factory_impl.mm
index 010c713090e5038dc90db131c8f621422d30c03b..20c35e887a0496ee609c077e3b0494bdded41dba 100644
--- a/content/app_shim_remote_cocoa/ns_view_bridge_factory_impl.mm
+++ b/content/app_shim_remote_cocoa/ns_view_bridge_factory_impl.mm
@@ -15,6 +15,7 @@
 #include "content/common/web_contents_ns_view_bridge.mojom.h"
 #include "content/public/browser/remote_cocoa.h"
 #include "content/public/browser/render_widget_host_view_mac_delegate.h"
+#include "electron/mas.h"
 #include "mojo/public/cpp/bindings/associated_receiver.h"
 #include "mojo/public/cpp/bindings/associated_remote.h"
 #include "mojo/public/cpp/bindings/pending_associated_receiver.h"
@@ -63,7 +64,9 @@ explicit RenderWidgetHostNSViewBridgeOwner(
       const RenderWidgetHostNSViewBridgeOwner&) = delete;
 
  private:
+#if !IS_MAS_BUILD()
   NSAccessibilityRemoteUIElement* __strong remote_accessibility_element_;
+#endif
   void OnMojoDisconnect() { delete this; }
 
   std::unique_ptr<blink::WebCoalescedInputEvent> TranslateEvent(
@@ -75,6 +78,7 @@ explicit RenderWidgetHostNSViewBridgeOwner(
   }
 
   id GetAccessibilityElement() override {
+#if !IS_MAS_BUILD()
     if (!remote_accessibility_element_) {
       base::ProcessId browser_pid = base::kNullProcessId;
       std::vector<uint8_t> element_token;
@@ -85,6 +89,9 @@ id GetAccessibilityElement() override {
           ui::RemoteAccessibility::GetRemoteElementFromToken(element_token);
     }
     return remote_accessibility_element_;
+#else
+    return nil;
+#endif
   }
 
   // RenderWidgetHostNSViewHostHelper implementation.
@@ -103,8 +110,10 @@ id GetFocusedBrowserAccessibilityElement() override {
     return [bridgedContentView accessibilityFocusedUIElement];
   }
   void SetAccessibilityWindow(NSWindow* window) override {
+#if !IS_MAS_BUILD()
     host_->SetRemoteAccessibilityWindowToken(
         ui::RemoteAccessibility::GetTokenForLocalElement(window));
+#endif
   }
 
   void ForwardKeyboardEvent(const input::NativeWebKeyboardEvent& key_event,
diff --git a/content/app_shim_remote_cocoa/render_widget_host_view_cocoa.mm b/content/app_shim_remote_cocoa/render_widget_host_view_cocoa.mm
index 6f3496b2541fa21fd0bba1d95026eab30e3ab96d..ef481cd946a15f5eaba928fa4e720e6c42556a93 100644
--- a/content/app_shim_remote_cocoa/render_widget_host_view_cocoa.mm
+++ b/content/app_shim_remote_cocoa/render_widget_host_view_cocoa.mm
@@ -34,6 +34,7 @@
 #import "content/public/browser/render_widget_host_view_mac_delegate.h"
 #include "content/public/browser/scoped_accessibility_mode.h"
 #include "content/public/common/content_features.h"
+#include "electron/mas.h"
 #include "skia/ext/skia_utils_mac.h"
 #include "third_party/blink/public/common/features.h"
 #include "third_party/blink/public/mojom/input/input_handler.mojom.h"
@@ -2085,15 +2086,21 @@ - (NSAccessibilityRole)accessibilityRole {
 // Since this implementation doesn't have to wait any IPC calls, this doesn't
 // make any key-typing jank. --hbono 7/23/09
 //
+#if !IS_MAS_BUILD()
 extern "C" {
 extern NSString* NSTextInputReplacementRangeAttributeName;
 }
+#endif
 
 - (NSArray*)validAttributesForMarkedText {
   // This code is just copied from WebKit except renaming variables.
   static NSArray* const kAttributes = @[
     NSUnderlineStyleAttributeName, NSUnderlineColorAttributeName,
+#if !IS_MAS_BUILD()
     NSMarkedClauseSegmentAttributeName, NSTextInputReplacementRangeAttributeName
+#else
+    NSMarkedClauseSegmentAttributeName
+#endif
   ];
   return kAttributes;
 }
diff --git a/content/browser/BUILD.gn b/content/browser/BUILD.gn
index 4d4d187ad8c62c4e18454b385c8003a5c478d3ad..20c94074e61cffcf2806fa6b713b0603631f98f8 100644
--- a/content/browser/BUILD.gn
+++ b/content/browser/BUILD.gn
@@ -343,6 +343,7 @@ source_set("browser") {
     "//ui/webui/resources",
     "//v8",
     "//v8:v8_version",
+    "//electron/build/config:generate_mas_config",
   ]
 
   public_deps = [
diff --git a/content/browser/renderer_host/render_widget_host_view_mac.h b/content/browser/renderer_host/render_widget_host_view_mac.h
index 29a5a99fa2c8e90812bd7ff40b153ead807bdbef..c8683c70f8cabfa89c95c28dc5fe59f42e9970c6 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.h
+++ b/content/browser/renderer_host/render_widget_host_view_mac.h
@@ -24,6 +24,7 @@
 #include "content/browser/renderer_host/text_input_manager.h"
 #include "content/common/content_export.h"
 #include "content/common/render_widget_host_ns_view.mojom.h"
+#include "electron/mas.h"
 #include "mojo/public/cpp/bindings/associated_receiver.h"
 #include "mojo/public/cpp/bindings/associated_remote.h"
 #include "third_party/blink/public/mojom/webshare/webshare.mojom.h"
@@ -58,7 +59,9 @@ struct CopyOutputBitmapWithMetadata;
 
 @protocol RenderWidgetHostViewMacDelegate;
 
+#if !IS_MAS_BUILD()
 @class NSAccessibilityRemoteUIElement;
+#endif
 @class RenderWidgetHostViewCocoa;
 
 namespace content {
@@ -680,9 +683,11 @@ class CONTENT_EXPORT RenderWidgetHostViewMac
   // EnsureSurfaceSynchronizedForWebTest().
   uint32_t latest_capture_sequence_number_ = 0u;
 
+#if !IS_MAS_BUILD()
   // Remote accessibility objects corresponding to the NSWindow that this is
   // displayed to the user in.
   NSAccessibilityRemoteUIElement* __strong remote_window_accessible_;
+#endif
 
   // Used to force the NSApplication's focused accessibility element to be the
   // content::BrowserAccessibilityCocoa accessibility tree when the NSView for
diff --git a/content/browser/renderer_host/render_widget_host_view_mac.mm b/content/browser/renderer_host/render_widget_host_view_mac.mm
index 503af3ee51ac6058a803a10e7c9cfea985866188..00f9abc97d2001fc0bd095d2c62097f2ed1ae047 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac.mm
+++ b/content/browser/renderer_host/render_widget_host_view_mac.mm
@@ -52,6 +52,7 @@
 #include "content/public/browser/render_widget_host.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/common/page_visibility_state.h"
+#include "electron/mas.h"
 #include "media/base/media_switches.h"
 #include "skia/ext/platform_canvas.h"
 #include "skia/ext/skia_utils_mac.h"
@@ -274,8 +275,10 @@
 void RenderWidgetHostViewMac::MigrateNSViewBridge(
     remote_cocoa::mojom::Application* remote_cocoa_application,
     uint64_t parent_ns_view_id) {
+#if !IS_MAS_BUILD()
   // Destroy the previous remote accessibility element.
   remote_window_accessible_ = nil;
+#endif
 
   // Reset `ns_view_` before resetting `remote_ns_view_` to avoid dangling
   // pointers. `ns_view_` gets reinitialized later in this method.
@@ -1655,10 +1658,12 @@ void CombineTextNodesAndMakeCallback(SpeechCallback callback,
 
 gfx::NativeViewAccessible
 RenderWidgetHostViewMac::AccessibilityGetNativeViewAccessibleForWindow() {
+#if !IS_MAS_BUILD()
   if (remote_window_accessible_) {
     return gfx::NativeViewAccessible(
         (id<NSAccessibility>)remote_window_accessible_);
   }
+#endif
   return gfx::NativeViewAccessible([GetInProcessNSView() window]);
 }
 
@@ -1710,9 +1715,11 @@ void CombineTextNodesAndMakeCallback(SpeechCallback callback,
 }
 
 void RenderWidgetHostViewMac::SetAccessibilityWindow(NSWindow* window) {
+#if !IS_MAS_BUILD()
   // When running in-process, just use the NSView's NSWindow as its own
   // accessibility element.
   remote_window_accessible_ = nil;
+#endif
 }
 
 bool RenderWidgetHostViewMac::SyncIsWidgetForMainFrame(
@@ -2215,20 +2222,26 @@ void CombineTextNodesAndMakeCallback(SpeechCallback callback,
 void RenderWidgetHostViewMac::GetRenderWidgetAccessibilityToken(
     GetRenderWidgetAccessibilityTokenCallback callback) {
   base::ProcessId pid = getpid();
+#if !IS_MAS_BUILD()
   id element_id = GetNativeViewAccessible().Get();
   std::vector<uint8_t> token =
       ui::RemoteAccessibility::GetTokenForLocalElement(element_id);
   std::move(callback).Run(pid, token);
+#else
+  std::move(callback).Run(pid, std::vector<uint8_t>());
+#endif
 }
 
 void RenderWidgetHostViewMac::SetRemoteAccessibilityWindowToken(
     const std::vector<uint8_t>& window_token) {
+#if !IS_MAS_BUILD()
   if (window_token.empty()) {
     remote_window_accessible_ = nil;
   } else {
     remote_window_accessible_ =
         ui::RemoteAccessibility::GetRemoteElementFromToken(window_token);
   }
+#endif
 }
 
 ///////////////////////////////////////////////////////////////////////////////
diff --git a/content/common/BUILD.gn b/content/common/BUILD.gn
index f57ce1a0430df7692be55685e79121ed604daf2a..3fbc26fb179a64a2f1eab027a05b16241c185b28 100644
--- a/content/common/BUILD.gn
+++ b/content/common/BUILD.gn
@@ -273,6 +273,7 @@ source_set("common") {
     "//ui/shell_dialogs",
     "//url",
     "//url/ipc:url_ipc",
+    "//electron/build/config:generate_mas_config",
   ]
 
   defines = []
diff --git a/content/renderer/BUILD.gn b/content/renderer/BUILD.gn
index 8404e4d6b8b2fc2d5f1597d5cbfcbcea2e692091..678121670b4977853e6fa1515f37d1ad21a3bd33 100644
--- a/content/renderer/BUILD.gn
+++ b/content/renderer/BUILD.gn
@@ -322,6 +322,7 @@ target(link_target_type, "renderer") {
     "//ui/surface",
     "//url",
     "//v8",
+    "//electron/build/config:generate_mas_config",
   ]
   allow_circular_includes_from = []
 
diff --git a/content/renderer/renderer_main_platform_delegate_mac.mm b/content/renderer/renderer_main_platform_delegate_mac.mm
index d4db3b179725cb96bcbd0f73db7d52ef8b7522db..703b0f56a61abac51961bfd918b7349b943900de 100644
--- a/content/renderer/renderer_main_platform_delegate_mac.mm
+++ b/content/renderer/renderer_main_platform_delegate_mac.mm
@@ -7,12 +7,15 @@
 #import <Cocoa/Cocoa.h>
 
 #include "base/check_op.h"
+#include "electron/mas.h"
 #include "sandbox/mac/seatbelt.h"
 #include "sandbox/mac/system_services.h"
 
+#if !IS_MAS_BUILD()
 extern "C" {
 CGError CGSSetDenyWindowServerConnections(bool);
 }
+#endif
 
 namespace content {
 
@@ -22,6 +25,7 @@
 // verifies there are no existing open connections), and then indicates that
 // Chrome should continue execution without access to launchservicesd.
 void DisableSystemServices() {
+#if !IS_MAS_BUILD()
   // Tell the WindowServer that we don't want to make any future connections.
   // This will return Success as long as there are no open connections, which
   // is what we want.
@@ -30,6 +34,7 @@ void DisableSystemServices() {
 
   sandbox::DisableLaunchServices();
   sandbox::DisableCoreServicesCheckFix();
+#endif
 }
 
 }  // namespace
diff --git a/content/renderer/theme_helper_mac.mm b/content/renderer/theme_helper_mac.mm
index a1068589ad844518038ee7bc15a3de9bc5cba525..1ff781c49f086ec8015c7d3c44567dbec3d00ff8 100644
--- a/content/renderer/theme_helper_mac.mm
+++ b/content/renderer/theme_helper_mac.mm
@@ -7,16 +7,28 @@
 #include <Cocoa/Cocoa.h>
 
 #include "base/strings/sys_string_conversions.h"
+#include "electron/mas.h"
 
+#if !IS_MAS_BUILD()
 extern "C" {
 bool CGFontRenderingGetFontSmoothingDisabled(void);
 }
-
+#endif
 namespace content {
 
 bool IsSubpixelAntialiasingAvailable() {
+#if !IS_MAS_BUILD()
   // See https://trac.webkit.org/changeset/239306/webkit for more info.
   return !CGFontRenderingGetFontSmoothingDisabled();
+#else
+  NSUserDefaults* defaults = [NSUserDefaults standardUserDefaults];
+  NSString *default_key = @"CGFontRenderingGetFontSmoothingDisabled";
+  // Check that key exists since boolForKey defaults to NO when the
+  // key is missing and this key in fact defaults to YES;
+  if ([defaults objectForKey:default_key] == nil)
+    return false;
+  return ![defaults boolForKey:default_key];
+#endif
 }
 
 }  // namespace content
diff --git a/content/test/BUILD.gn b/content/test/BUILD.gn
index 88911eb5fe3d6e6423b12e2116704988cd032592..5852f0936d8a8de32fcce44f9833fca8aa4fcd7f 100644
--- a/content/test/BUILD.gn
+++ b/content/test/BUILD.gn
@@ -703,6 +703,7 @@ static_library("test_support") {
     "//url",
     "//url/mojom:url_mojom_gurl",
     "//v8",
+    "//electron/build/config:generate_mas_config"
   ]
 
   data_deps = [
@@ -1178,6 +1179,8 @@ static_library("browsertest_support") {
   # TODO(crbug.com/40031409): Fix code that adds exit-time destructors and
   # enable the diagnostic by removing this line.
   configs += [ "//build/config/compiler:no_exit_time_destructors" ]
+
+  deps += ["//electron/build/config:generate_mas_config"]
 }
 
 mojom("content_test_mojo_bindings") {
@@ -2066,6 +2069,7 @@ test("content_browsertests") {
     "//ui/shell_dialogs",
     "//ui/snapshot",
     "//ui/webui:test_support",
+    "//electron/build/config:generate_mas_config"
   ]
 
   if (!(is_chromeos && target_cpu == "arm64" && current_cpu == "arm")) {
@@ -3403,6 +3407,7 @@ test("content_unittests") {
     "//ui/shell_dialogs",
     "//ui/webui:test_support",
     "//url",
+    "//electron/build/config:generate_mas_config",
   ]
 
   if (is_chromeos) {
diff --git a/content/web_test/BUILD.gn b/content/web_test/BUILD.gn
index 23eccafa5fbc79d633168923855644f5811a4b80..7174d4816765fa2d3cde99a6756048a42b0c4a5a 100644
--- a/content/web_test/BUILD.gn
+++ b/content/web_test/BUILD.gn
@@ -228,6 +228,7 @@ static_library("web_test_browser") {
     "//ui/gl",
     "//ui/shell_dialogs",
     "//url",
+    "//electron/build/config:generate_mas_config",
   ]
 
   if (is_mac) {
diff --git a/device/bluetooth/BUILD.gn b/device/bluetooth/BUILD.gn
index 3504d7197bd3225b6b83d7e057f389d8327b9ff7..92547d8bc700f3139f4bbc77d621152e0bc2a81c 100644
--- a/device/bluetooth/BUILD.gn
+++ b/device/bluetooth/BUILD.gn
@@ -257,6 +257,7 @@ component("bluetooth") {
       "CoreBluetooth.framework",
       "Foundation.framework",
     ]
+    deps += ["//electron/build/config:generate_mas_config"]
   }
 
   if (is_mac) {
diff --git a/device/bluetooth/bluetooth_adapter_mac.mm b/device/bluetooth/bluetooth_adapter_mac.mm
index f300e8d331057e894b43b74944e5052c39206844..4ff5277d550485cd79c5b5316d89c730ba709254 100644
--- a/device/bluetooth/bluetooth_adapter_mac.mm
+++ b/device/bluetooth/bluetooth_adapter_mac.mm
@@ -39,7 +39,9 @@
 #include "device/bluetooth/bluetooth_discovery_session_outcome.h"
 #include "device/bluetooth/bluetooth_socket_mac.h"
 #include "device/bluetooth/public/cpp/bluetooth_address.h"
+#include "electron/mas.h"
 
+#if !IS_MAS_BUILD()
 extern "C" {
 // Undocumented IOBluetooth Preference API [1]. Used by `blueutil` [2] and
 // `Karabiner` [3] to programmatically control the Bluetooth state. Calling the
@@ -53,6 +55,7 @@
 // [4] https://support.apple.com/kb/PH25091
 void IOBluetoothPreferenceSetControllerPowerState(int state);
 }
+#endif
 
 // A simple helper class that forwards any Bluetooth device connect notification
 // to its wrapped |_adapter|.
@@ -162,8 +165,10 @@ bool IsDeviceSystemPaired(const std::string& device_address) {
     : controller_state_function_(
           base::BindRepeating(&BluetoothAdapterMac::GetHostControllerState,
                               base::Unretained(this))),
+#if !IS_MAS_BUILD()
       power_state_function_(
           base::BindRepeating(IOBluetoothPreferenceSetControllerPowerState)),
+#endif
       device_paired_status_callback_(
           base::BindRepeating(&IsDeviceSystemPaired)) {
 }
@@ -314,8 +319,12 @@ bool IsDeviceSystemPaired(const std::string& device_address) {
 }
 
 bool BluetoothAdapterMac::SetPoweredImpl(bool powered) {
+#if !IS_MAS_BUILD()
   power_state_function_.Run(base::strict_cast<int>(powered));
   return true;
+#else
+  return false;
+#endif
 }
 
 base::WeakPtr<BluetoothLowEnergyAdapterApple>
diff --git a/gpu/ipc/service/BUILD.gn b/gpu/ipc/service/BUILD.gn
index 327c2a54f2977ec99885c8c50709129cd5dcd87f..67c1b8a68dec740d0230d6b2396234b9a8b39a8a 100644
--- a/gpu/ipc/service/BUILD.gn
+++ b/gpu/ipc/service/BUILD.gn
@@ -119,6 +119,7 @@ component("service") {
         "QuartzCore.framework",
       ]
       defines += [ "GL_SILENCE_DEPRECATION" ]
+      deps += ["//electron/build/config:generate_mas_config"]
     }
     if (is_ios) {
       sources += [ "image_transport_surface_ios.mm" ]
diff --git a/gpu/ipc/service/image_transport_surface_overlay_mac.h b/gpu/ipc/service/image_transport_surface_overlay_mac.h
index 8b7a675d95ad36cbb9528bc5bc7ef05e5124e5a3..ed6a9a326b82b177059317dc4bc54b102f9bcc78 100644
--- a/gpu/ipc/service/image_transport_surface_overlay_mac.h
+++ b/gpu/ipc/service/image_transport_surface_overlay_mac.h
@@ -8,6 +8,7 @@
 #include <vector>
 
 #include "base/memory/weak_ptr.h"
+#include "electron/mas.h"
 #include "gpu/ipc/service/command_buffer_stub.h"
 #include "gpu/ipc/service/image_transport_surface.h"
 #include "ui/gfx/ca_layer_result.h"
@@ -27,7 +28,9 @@
 #include <BrowserEngineKit/BrowserEngineKit.h>
 #endif
 
+#if !IS_MAS_BUILD()
 @class CAContext;
+#endif
 @class CALayer;
 
 namespace ui {
diff --git a/media/audio/BUILD.gn b/media/audio/BUILD.gn
index 9388ffac4f70746b04e533b51faf4f2d55ab3358..98f45dc973159b5823d8a0433dfd4bc634874b1e 100644
--- a/media/audio/BUILD.gn
+++ b/media/audio/BUILD.gn
@@ -203,6 +203,7 @@ source_set("audio") {
       "CoreMedia.framework",
     ]
     weak_frameworks = [ "ScreenCaptureKit.framework" ]  # macOS 13.0
+    deps += ["//electron/build/config:generate_mas_config"]
   }
 
   if (is_ios) {
diff --git a/media/audio/apple/audio_low_latency_input.cc b/media/audio/apple/audio_low_latency_input.cc
index 686c7e9b126260720424cd72d91a3f27002c5af8..e181ff1b909d928a3aa3a913a267d01f0fd647ec 100644
--- a/media/audio/apple/audio_low_latency_input.cc
+++ b/media/audio/apple/audio_low_latency_input.cc
@@ -29,6 +29,7 @@
 #include "base/strings/sys_string_conversions.h"
 #include "base/time/time.h"
 #include "base/trace_event/trace_event.h"
+#include "electron/mas.h"
 #include "media/audio/apple/audio_manager_apple.h"
 #include "media/audio/apple/scoped_audio_unit.h"
 #include "media/base/audio_bus.h"
@@ -42,19 +43,23 @@
 
 namespace {
 extern "C" {
+#if !IS_MAS_BUILD()
 // See:
 // https://trac.webkit.org/browser/webkit/trunk/Source/WebCore/PAL/pal/spi/cf/CoreAudioSPI.h?rev=228264
 OSStatus AudioDeviceDuck(AudioDeviceID inDevice,
                          Float32 inDuckedLevel,
                          const AudioTimeStamp* __nullable inStartTime,
                          Float32 inRampDuration) __attribute__((weak_import));
+#endif
 }
 
 void UndoDucking(AudioDeviceID output_device_id) {
+#if !IS_MAS_BUILD()
   if (AudioDeviceDuck != nullptr) {
     // Ramp the volume back up over half a second.
     AudioDeviceDuck(output_device_id, 1.0, nullptr, 0.5);
   }
+#endif
 }
 }  // namespace
 #endif
diff --git a/net/dns/BUILD.gn b/net/dns/BUILD.gn
index 5ed1605df7339b504838dfd949772b47ed72a89f..07ccbd74e0835f20edfeef76d0e5e1241a48a65c 100644
--- a/net/dns/BUILD.gn
+++ b/net/dns/BUILD.gn
@@ -197,6 +197,8 @@ source_set("dns") {
     ":host_resolver_manager",
     ":mdns_client",
   ]
+
+  deps += ["//electron/build/config:generate_mas_config"]
 }
 
 # The standard API of net/dns.
diff --git a/net/dns/dns_config_service_posix.cc b/net/dns/dns_config_service_posix.cc
index 70d5665ad7b9ef62370497636af919ede2508ad4..f4dc3e2b8053cdb3e8c439ab1a1d6369a8e6a7dc 100644
--- a/net/dns/dns_config_service_posix.cc
+++ b/net/dns/dns_config_service_posix.cc
@@ -28,6 +28,7 @@
 #include "base/threading/scoped_blocking_call.h"
 #include "base/time/time.h"
 #include "build/build_config.h"
+#include "electron/mas.h"
 #include "net/base/ip_endpoint.h"
 #include "net/dns/dns_config.h"
 #include "net/dns/dns_hosts.h"
@@ -135,8 +136,8 @@ class DnsConfigServicePosix::Watcher : public DnsConfigService::Watcher {
 
   bool Watch() override {
     CheckOnCorrectSequence();
-
     bool success = true;
+#if !IS_MAS_BUILD()
     if (!config_watcher_.Watch(base::BindRepeating(&Watcher::OnConfigChanged,
                                                    base::Unretained(this)))) {
       LOG(ERROR) << "DNS config watch failed to start.";
@@ -153,6 +154,7 @@ class DnsConfigServicePosix::Watcher : public DnsConfigService::Watcher {
       success = false;
     }
 #endif  // !BUILDFLAG(IS_IOS)
+#endif
     return success;
   }
 
diff --git a/sandbox/mac/BUILD.gn b/sandbox/mac/BUILD.gn
index d145bdb3f879ae7e2d77f3b58fe7abd09d6f7255..8973f310aa62b59bc829e8e0f8ed068bfffa3f2b 100644
--- a/sandbox/mac/BUILD.gn
+++ b/sandbox/mac/BUILD.gn
@@ -25,6 +25,7 @@ component("seatbelt") {
   libs = [ "sandbox" ]
   deps = [ ":seatbelt_export" ]
   defines = [ "SEATBELT_IMPLEMENTATION" ]
+  deps += ["//electron/build/config:generate_mas_config"]
 }
 
 component("seatbelt_extension") {
@@ -38,6 +39,7 @@ component("seatbelt_extension") {
   libs = [ "sandbox" ]
   public_deps = [ "//base" ]
   defines = [ "SEATBELT_IMPLEMENTATION" ]
+  deps += ["//electron/build/config:generate_mas_config"]
 }
 
 component("system_services") {
@@ -52,6 +54,7 @@ component("system_services") {
   deps = [ ":seatbelt_export" ]
   public_deps = [ "//base" ]
   defines = [ "SEATBELT_IMPLEMENTATION" ]
+  deps += ["//electron/build/config:generate_mas_config"]
 }
 
 source_set("sandbox_unittests") {
diff --git a/sandbox/mac/sandbox_logging.cc b/sandbox/mac/sandbox_logging.cc
index 950cf7cfee4e11766dccf5c0bf3f15a8562f0f1e..a5adaaabdbbd91fedbc4cb679c865bc342536090 100644
--- a/sandbox/mac/sandbox_logging.cc
+++ b/sandbox/mac/sandbox_logging.cc
@@ -21,6 +21,7 @@
 #include <string>
 
 #include "build/build_config.h"
+#include "electron/mas.h"
 #include "sandbox/mac/sandbox_crash_message.h"
 
 #if defined(ARCH_CPU_X86_64)
@@ -38,9 +39,11 @@
   }
 #endif
 
+#if !IS_MAS_BUILD()
 extern "C" {
 void abort_report_np(const char*, ...);
 }
+#endif
 
 namespace sandbox::logging {
 
@@ -81,9 +84,11 @@ void SendOsLog(Level level, const char* message) {
     sandbox::crash_message::SetCrashMessage(message);
   }
 
+#if !IS_MAS_BUILD()
   if (level == Level::FATAL) {
     abort_report_np(message);
   }
+#endif
 }
 
 // |error| is strerror(errno) when a P* logging function is called. Pass
diff --git a/sandbox/mac/sandbox_serializer.cc b/sandbox/mac/sandbox_serializer.cc
index 0e6e650f88e6aadd46bec96a8b41768c37d7cc6a..a6830e3f886e408c254ccd1c2b1d5c15cd3bcb92 100644
--- a/sandbox/mac/sandbox_serializer.cc
+++ b/sandbox/mac/sandbox_serializer.cc
@@ -8,6 +8,7 @@
 #include <string>
 #include <vector>
 
+#include "electron/mas.h"
 #include "sandbox/mac/sandbox_logging.h"
 #include "sandbox/mac/seatbelt.h"
 
@@ -193,6 +194,7 @@ SandboxSerializer::DeserializePolicy(const std::string& serialized_policy,
 // static
 bool SandboxSerializer::ApplySerializedPolicy(
     const std::string& serialized_policy) {
+#if !IS_MAS_BUILD()
   std::string error;
   std::optional<DeserializedPolicy> deserialized_policy =
       DeserializePolicy(serialized_policy, error);
@@ -223,6 +225,9 @@ bool SandboxSerializer::ApplySerializedPolicy(
       break;
   }
   return true;
+#else
+  return true;
+#endif
 }
 
 }  // namespace sandbox
diff --git a/sandbox/mac/seatbelt.cc b/sandbox/mac/seatbelt.cc
index e9321ba5fc0f1b24b2d990ecb27c8aaa1c8b970b..51df9671a507acd115f09a50c2d6e987fb4183c2 100644
--- a/sandbox/mac/seatbelt.cc
+++ b/sandbox/mac/seatbelt.cc
@@ -4,6 +4,8 @@
 
 #include "sandbox/mac/seatbelt.h"
 
+#include "electron/mas.h"
+
 #include <errno.h>
 #include <unistd.h>
 
@@ -12,7 +14,7 @@
 
 extern "C" {
 #include <sandbox.h>
-
+#if !IS_MAS_BUILD()
 int sandbox_init_with_parameters(const char* profile,
                                  uint64_t flags,
                                  const char* const parameters[],
@@ -58,13 +60,14 @@ sandbox_profile_t* sandbox_compile_string(const char* data,
                                           char** error);
 int sandbox_apply(sandbox_profile_t*);
 void sandbox_free_profile(sandbox_profile_t*);
-
+#endif
 }  // extern "C"
 
 namespace sandbox {
 
 namespace {
 
+#if !IS_MAS_BUILD()
 // `managed_errorbuf` uses a unique_ptr with a deleter to ensure that memory is
 // freed using the sandbox library's deallocation function to prevent unexpected
 // behavior.
@@ -107,36 +110,48 @@ bool HandleSandboxErrno(int rv, const char* message, std::string* error) {
   }
   return false;
 }
-
+#endif
 }  // namespace
 
 // static
 Seatbelt::Parameters Seatbelt::Parameters::Create() {
   Parameters params;
+#if !IS_MAS_BUILD()
   params.params_ = ::sandbox_create_params();
+#endif
   return params;
 }
 
 Seatbelt::Parameters::Parameters() = default;
 
 Seatbelt::Parameters::Parameters(Seatbelt::Parameters&& other) {
+#if !IS_MAS_BUILD()
   params_ = std::exchange(other.params_, nullptr);
+#endif
 }
 
 Seatbelt::Parameters& Seatbelt::Parameters::operator=(
     Seatbelt::Parameters&& other) {
+#if !IS_MAS_BUILD()
   params_ = std::exchange(other.params_, nullptr);
+#endif
   return *this;
 }
 
 bool Seatbelt::Parameters::Set(const char* key, const char* value) {
+#if !IS_MAS_BUILD()
   return ::sandbox_set_param(params_, key, value) == 0;
+#else
+  return true;
+#endif
 }
 
 Seatbelt::Parameters::~Parameters() {
+#if !IS_MAS_BUILD()
   if (params_) {
     ::sandbox_free_params(params_);
   }
+#endif
 }
 
 // Initialize the static member variables.
@@ -147,6 +162,7 @@ const char* Seatbelt::kProfilePureComputation = kSBXProfilePureComputation;
 
 // static
 bool Seatbelt::Init(const char* profile, uint64_t flags, std::string* error) {
+#if !IS_MAS_BUILD()
 // OS X deprecated these functions, but did not provide a suitable replacement,
 // so ignore the deprecation warning.
 #pragma clang diagnostic push
@@ -156,6 +172,9 @@ bool Seatbelt::Init(const char* profile, uint64_t flags, std::string* error) {
   return HandleSandboxResult(
       rv, std::unique_ptr<char, sandbox_error_deleter>(errorbuf), error);
 #pragma clang diagnostic pop
+#else
+  return true;
+#endif
 }
 
 // static
@@ -163,17 +182,22 @@ bool Seatbelt::InitWithParams(const std::string& profile,
                               uint64_t flags,
                               const std::vector<std::string>& parameters,
                               std::string* error) {
+#if !IS_MAS_BUILD()
   std::vector<const char*> weak_params;
   for (const std::string& param : parameters) {
     weak_params.push_back(param.c_str());
   }
   // The parameters array must be null terminated.
   weak_params.push_back(nullptr);
+
   char* errorbuf = nullptr;
   int rv = ::sandbox_init_with_parameters(profile.c_str(), flags,
                                           weak_params.data(), &errorbuf);
   return HandleSandboxResult(
       rv, std::unique_ptr<char, sandbox_error_deleter>(errorbuf), error);
+#else
+  return true;
+#endif
 }
 
 // static
@@ -181,6 +205,7 @@ bool Seatbelt::Compile(const char* profile,
                        const Seatbelt::Parameters& params,
                        std::string& compiled_profile,
                        std::string* error) {
+#if !IS_MAS_BUILD()
   char* errorbuf = nullptr;
   sandbox_profile_t* sandbox_profile =
       ::sandbox_compile_string(profile, params.params(), &errorbuf);
@@ -192,23 +217,32 @@ bool Seatbelt::Compile(const char* profile,
   compiled_profile.assign(reinterpret_cast<const char*>(sandbox_profile->data),
                           sandbox_profile->size);
   ::sandbox_free_profile(sandbox_profile);
+#endif
   return true;
 }
 
 // static
 bool Seatbelt::ApplyCompiledProfile(const std::string& profile,
                                     std::string* error) {
+#if !IS_MAS_BUILD()
   sandbox_profile_t sbox_profile = {
       .builtin = nullptr,
       .data = reinterpret_cast<const uint8_t*>(profile.data()),
       .size = profile.size()};
   return HandleSandboxErrno(::sandbox_apply(&sbox_profile),
                             "sandbox_apply: ", error);
+#else
+  return true;
+#endif
 }
 
 // static
 bool Seatbelt::IsSandboxed() {
+#if !IS_MAS_BUILD()
   return ::sandbox_check(getpid(), NULL, 0);
+#else
+  return true;
+#endif
 }
 
 }  // namespace sandbox
diff --git a/sandbox/mac/seatbelt_extension.cc b/sandbox/mac/seatbelt_extension.cc
index 79edca9ca521d1bc2ff343967348eb98039b292a..23f9410ee66024e2c6b0b6b2b356a67b0ae2eba7 100644
--- a/sandbox/mac/seatbelt_extension.cc
+++ b/sandbox/mac/seatbelt_extension.cc
@@ -9,8 +9,10 @@
 #include "base/check.h"
 #include "base/memory/ptr_util.h"
 #include "base/notreached.h"
+#include "electron/mas.h"
 #include "sandbox/mac/seatbelt_extension_token.h"
 
+#if !IS_MAS_BUILD()
 // libsandbox private API.
 extern "C" {
 extern const char* APP_SANDBOX_READ;
@@ -22,6 +24,7 @@ char* sandbox_extension_issue_file(const char* type,
                                    const char* path,
                                    uint32_t flags);
 }
+#endif
 
 namespace sandbox {
 
@@ -50,7 +53,11 @@ std::unique_ptr<SeatbeltExtension> SeatbeltExtension::FromToken(
 
 bool SeatbeltExtension::Consume() {
   DCHECK(!token_.empty());
+#if !IS_MAS_BUILD()
   handle_ = sandbox_extension_consume(token_.c_str());
+#else
+  handle_ = -1;
+#endif
   return handle_ > 0;
 }
 
@@ -62,7 +69,11 @@ bool SeatbeltExtension::ConsumePermanently() {
 }
 
 bool SeatbeltExtension::Revoke() {
+#if !IS_MAS_BUILD()
   int rv = sandbox_extension_release(handle_);
+#else
+  int rv = -1;
+#endif
   handle_ = 0;
   token_.clear();
   return rv == 0;
@@ -80,12 +91,14 @@ SeatbeltExtension::SeatbeltExtension(const std::string& token)
 char* SeatbeltExtension::IssueToken(SeatbeltExtension::Type type,
                                     const std::string& resource) {
   switch (type) {
+#if !IS_MAS_BUILD()
     case FILE_READ:
       return sandbox_extension_issue_file(APP_SANDBOX_READ, resource.c_str(),
                                           0);
     case FILE_READ_WRITE:
       return sandbox_extension_issue_file(APP_SANDBOX_READ_WRITE,
                                           resource.c_str(), 0);
+#endif
     default:
       NOTREACHED();
   }
diff --git a/sandbox/mac/system_services.cc b/sandbox/mac/system_services.cc
index eb81a70e4d5d5cd3e6ae9b45f8cd1c795ea76c51..9921ccb10d3455600eddd85f77f10228016389af 100644
--- a/sandbox/mac/system_services.cc
+++ b/sandbox/mac/system_services.cc
@@ -8,7 +8,9 @@
 #include <CoreFoundation/CoreFoundation.h>
 
 #include "base/apple/osstatus_logging.h"
+#include "electron/mas.h"
 
+#if !IS_MAS_BUILD()
 extern "C" {
 OSStatus SetApplicationIsDaemon(Boolean isDaemon);
 void _LSSetApplicationLaunchServicesServerConnectionStatus(
@@ -19,10 +21,12 @@ void _LSSetApplicationLaunchServicesServerConnectionStatus(
 // https://github.com/WebKit/WebKit/blob/24aaedc770d192d03a07ba4a71727274aaa8fc07/Source/WebKit/WebProcess/cocoa/WebProcessCocoa.mm#L840
 void _CSCheckFixDisable();
 }  // extern "C"
+#endif
 
 namespace sandbox {
 
 void DisableLaunchServices() {
+  #if !IS_MAS_BUILD()
   // Allow the process to continue without a LaunchServices ASN. The
   // INIT_Process function in HIServices will abort if it cannot connect to
   // launchservicesd to get an ASN. By setting this flag, HIServices skips
@@ -36,10 +40,13 @@ void DisableLaunchServices() {
       0, ^bool(CFDictionaryRef options) {
         return false;
       });
+  #endif
 }
 
 void DisableCoreServicesCheckFix() {
+#if !IS_MAS_BUILD()
   _CSCheckFixDisable();
+#endif
 }
 
 }  // namespace sandbox
diff --git a/third_party/blink/renderer/core/BUILD.gn b/third_party/blink/renderer/core/BUILD.gn
index e54ba53ed4866e568ae5c2dfe65e72adfe253e03..07d046634534efb28ee4584dd1b11678f7473e8f 100644
--- a/third_party/blink/renderer/core/BUILD.gn
+++ b/third_party/blink/renderer/core/BUILD.gn
@@ -428,6 +428,7 @@ component("core") {
     "//ui/gfx/geometry",
     "//ui/gfx/geometry:geometry_skia",
     "//ui/strings",
+    "//electron/build/config:generate_mas_config",
   ]
 
   if (is_mac) {
diff --git a/third_party/blink/renderer/core/editing/build.gni b/third_party/blink/renderer/core/editing/build.gni
index 4f04476e9175bae9e89eb9ea4316bffe49a9eb91..e77615c7b26518f4930ac1b004b413173fa0f46b 100644
--- a/third_party/blink/renderer/core/editing/build.gni
+++ b/third_party/blink/renderer/core/editing/build.gni
@@ -362,10 +362,14 @@ blink_core_sources_editing = [
 if (is_mac) {
   blink_core_sources_editing += [
     "commands/smart_replace_cf.cc",
-    "kill_ring_mac.mm",
     "substring_util.h",
     "substring_util.mm",
   ]
+  if (is_mas_build) {
+    blink_core_sources_editing += [ "kill_ring_mac.mm" ]
+  } else {
+    blink_core_sources_editing += [ "kill_ring_none.cc" ]
+  }
 } else {
   blink_core_sources_editing += [ "kill_ring_none.cc" ]
 }
diff --git a/ui/accelerated_widget_mac/BUILD.gn b/ui/accelerated_widget_mac/BUILD.gn
index 0f8a6f75b7f01029adc2f5fd23559bacce19cf72..cf66c2f4f02a8e21cc83c3b7389fc5156bcd93ba 100644
--- a/ui/accelerated_widget_mac/BUILD.gn
+++ b/ui/accelerated_widget_mac/BUILD.gn
@@ -83,6 +83,7 @@ component("accelerated_widget_mac") {
     "//ui/gfx",
     "//ui/gfx/geometry",
     "//ui/gl",
+    "//electron/build/config:generate_mas_config",
   ]
 }
 
diff --git a/ui/accelerated_widget_mac/ca_layer_tree_coordinator.h b/ui/accelerated_widget_mac/ca_layer_tree_coordinator.h
index d5f35d2ccfb21b231e235dbfae3eee96a488eb20..14592180823131ca87bc95300c8d9a82451e6628 100644
--- a/ui/accelerated_widget_mac/ca_layer_tree_coordinator.h
+++ b/ui/accelerated_widget_mac/ca_layer_tree_coordinator.h
@@ -8,13 +8,16 @@
 #include <queue>
 
 #include "base/containers/queue.h"
+#include "electron/mas.h"
 #include "ui/accelerated_widget_mac/accelerated_widget_mac_export.h"
 #include "ui/gfx/ca_layer_result.h"
 #include "ui/gfx/presentation_feedback.h"
 #include "ui/gl/gl_context.h"
 #include "ui/gl/presenter.h"
 
+#if !IS_MAS_BUILD()
 @class CAContext;
+#endif
 @class CALayer;
 @protocol MTLDevice;
 
@@ -119,7 +122,9 @@ class ACCELERATED_WIDGET_MAC_EXPORT CALayerTreeCoordinator {
   // both the current tree and the pending trees.
   size_t presented_ca_layer_trees_max_length_ = 2;
 
+#if !IS_MAS_BUILD()
   CAContext* __strong ca_context_;
+#endif
 
   // The root CALayer to display the current frame. This does not change
   // over the lifetime of the object.
diff --git a/ui/accelerated_widget_mac/ca_layer_tree_coordinator.mm b/ui/accelerated_widget_mac/ca_layer_tree_coordinator.mm
index 5e50feb42b4a49b03a75b510bb3ddc269282aa2f..1519401a362530b7107eab17c28b63486e7455ff 100644
--- a/ui/accelerated_widget_mac/ca_layer_tree_coordinator.mm
+++ b/ui/accelerated_widget_mac/ca_layer_tree_coordinator.mm
@@ -10,6 +10,7 @@
 #include "base/mac/mac_util.h"
 #include "base/task/single_thread_task_runner.h"
 #include "base/trace_event/trace_event.h"
+#include "electron/mas.h"
 #include "ui/accelerated_widget_mac/ca_renderer_layer_tree.h"
 #include "ui/base/cocoa/animation_utils.h"
 #include "ui/base/cocoa/remote_layer_api.h"
@@ -37,6 +38,7 @@
       buffer_presented_callback_(buffer_presented_callback),
       gl_make_current_callback_(gl_make_current_callback),
       metal_device_(metal_device) {
+#if !IS_MAS_BUILD()
   if (allow_remote_layers_) {
     root_ca_layer_ = [[CALayer alloc] init];
 #if BUILDFLAG(IS_MAC)
@@ -65,6 +67,7 @@
 #endif
     ca_context_.layer = root_ca_layer_;
   }
+#endif
 }
 
 CALayerTreeCoordinator::~CALayerTreeCoordinator() = default;
@@ -207,9 +210,13 @@
     TRACE_EVENT_INSTANT2("test_gpu", "SwapBuffers", TRACE_EVENT_SCOPE_THREAD,
                          "GLImpl", static_cast<int>(gl::GetGLImplementation()),
                          "width", pixel_size_.width());
+#if !IS_MAS_BUILD()
     if (allow_remote_layers_) {
       params.ca_context_id = [ca_context_ contextId];
     } else {
+#else
+    if (true) {
+#endif
       IOSurfaceRef io_surface = frame.layer_tree->GetContentIOSurface();
       if (io_surface) {
         DCHECK(!allow_remote_layers_);
diff --git a/ui/accelerated_widget_mac/display_ca_layer_tree.mm b/ui/accelerated_widget_mac/display_ca_layer_tree.mm
index dcf493d62990018040a3f84b6f875af737bd2214..3d1c4dcc9ee0bbfdac15f40d9c74e9f342a59e39 100644
--- a/ui/accelerated_widget_mac/display_ca_layer_tree.mm
+++ b/ui/accelerated_widget_mac/display_ca_layer_tree.mm
@@ -12,6 +12,7 @@
 #include "base/mac/mac_util.h"
 #include "base/trace_event/trace_event.h"
 #include "build/build_config.h"
+#include "electron/mas.h"
 #include "ui/base/cocoa/animation_utils.h"
 #include "ui/base/cocoa/remote_layer_api.h"
 #include "ui/gfx/geometry/dip_util.h"
@@ -121,6 +122,7 @@ - (void)setContentsChanged;
 }
 
 void DisplayCALayerTree::GotCALayerFrame(uint32_t ca_context_id) {
+#if !IS_MAS_BUILD()
   // Early-out if the remote layer has not changed.
   if (remote_layer_.contextId == ca_context_id) {
     return;
@@ -150,6 +152,9 @@ - (void)setContentsChanged;
     [io_surface_layer_ removeFromSuperlayer];
     io_surface_layer_ = nil;
   }
+#else
+  NOTREACHED() << "Remote layer is being used in MAS build";
+#endif
 }
 
 void DisplayCALayerTree::GotIOSurfaceFrame(
diff --git a/ui/accessibility/platform/BUILD.gn b/ui/accessibility/platform/BUILD.gn
index 54d483d6b3f1a56573e21b1f873b8dee8fc25a0f..33bc8c9ef097a907060ed347dca2ad46b6d081f5 100644
--- a/ui/accessibility/platform/BUILD.gn
+++ b/ui/accessibility/platform/BUILD.gn
@@ -299,6 +299,7 @@ component("platform") {
         "AppKit.framework",
         "Foundation.framework",
       ]
+      deps += ["//electron/build/config:generate_mas_config"]
     }
 
     if (is_ios) {
diff --git a/ui/accessibility/platform/browser_accessibility_manager_mac.mm b/ui/accessibility/platform/browser_accessibility_manager_mac.mm
index 3e6426f895b55168834809ed6b91916f447d7ea3..33ec3f6ce4e5a69760779d28a3ae2b07a183afa4 100644
--- a/ui/accessibility/platform/browser_accessibility_manager_mac.mm
+++ b/ui/accessibility/platform/browser_accessibility_manager_mac.mm
@@ -14,6 +14,7 @@
 #include "base/task/single_thread_task_runner.h"
 #include "base/task/task_traits.h"
 #include "base/time/time.h"
+#include "electron/mas.h"
 #include "ui/accelerated_widget_mac/accelerated_widget_mac.h"
 #include "ui/accessibility/accessibility_features.h"
 #include "ui/accessibility/ax_role_properties.h"
@@ -22,7 +23,9 @@
 #include "ui/accessibility/platform/ax_private_webkit_constants_mac.h"
 #import "ui/accessibility/platform/browser_accessibility_cocoa.h"
 #import "ui/accessibility/platform/browser_accessibility_mac.h"
+#if !IS_MAS_BUILD()
 #include "ui/base/cocoa/remote_accessibility_api.h"
+#endif
 
 namespace {
 
@@ -231,6 +234,7 @@ void PostAnnouncementNotification(NSString* announcement,
         return;
       }
 
+#if !IS_MAS_BUILD()
       BrowserAccessibilityManager* root_manager = GetManagerForRootFrame();
       if (root_manager) {
         BrowserAccessibilityManagerMac* root_manager_mac =
@@ -253,6 +257,7 @@ void PostAnnouncementNotification(NSString* announcement,
           return;
         }
       }
+#endif
 
       // Use native VoiceOver support for live regions.
       BrowserAccessibilityCocoa* retained_node = native_node;
@@ -696,6 +701,7 @@ void PostAnnouncementNotification(NSString* announcement,
     return window == [NSApp accessibilityFocusedWindow];
   }
 
+#if !IS_MAS_BUILD()
   // TODO(accessibility): We need a solution to the problem described below.
   // If the window is NSAccessibilityRemoteUIElement, there are some challenges:
   // 1. NSApp is the browser which spawned the PWA, and what it considers the
@@ -724,6 +730,7 @@ void PostAnnouncementNotification(NSString* announcement,
   if ([window isKindOfClass:[NSAccessibilityRemoteUIElement class]]) {
     return true;
   }
+#endif
 
   return false;
 }
diff --git a/ui/accessibility/platform/inspect/ax_transform_mac.mm b/ui/accessibility/platform/inspect/ax_transform_mac.mm
index 6846060ef9622d8fc8d1d6c8da16e2f1b785e6bd..05c22db87e882b246bd7034e027cf1495376b6c6 100644
--- a/ui/accessibility/platform/inspect/ax_transform_mac.mm
+++ b/ui/accessibility/platform/inspect/ax_transform_mac.mm
@@ -11,6 +11,7 @@
 
 #include "base/apple/foundation_util.h"
 #include "base/strings/sys_string_conversions.h"
+#include "electron/mas.h"
 #include "ui/accessibility/ax_range.h"
 #include "ui/accessibility/platform/ax_platform_node.h"
 #include "ui/accessibility/platform/ax_platform_node_cocoa.h"
@@ -111,6 +112,7 @@
     }
   }
 
+#if !IS_MAS_BUILD()
   // AXTextMarker
   if (IsAXTextMarker(value)) {
     return AXTextMarkerToBaseValue(value, indexer);
@@ -120,6 +122,7 @@
   if (IsAXTextMarkerRange(value)) {
     return AXTextMarkerRangeToBaseValue(value, indexer);
   }
+#endif
 
   // Accessible object
   if (AXElementWrapper::IsValidElement(value)) {
diff --git a/ui/base/BUILD.gn b/ui/base/BUILD.gn
index 1428a0aa8d233062990e825050e71d3e3b6dd6f0..009d3446ae976150b25c92ee50590f0926956bca 100644
--- a/ui/base/BUILD.gn
+++ b/ui/base/BUILD.gn
@@ -355,6 +355,13 @@ component("base") {
     ]
   }
 
+  if (is_mas_build) {
+    sources -= [
+      "cocoa/remote_accessibility_api.h",
+      "cocoa/remote_accessibility_api.mm",
+    ]
+  }
+
   if (is_ios) {
     sources += [
       "device_form_factor_ios.mm",
@@ -503,6 +510,12 @@ component("base") {
     "//url",
   ]
 
+  if (is_mac) {
+    deps += [
+      "//electron/build/config:generate_mas_config"
+    ]
+  }
+
   if (is_debug || dcheck_always_on) {
     deps += [ "//third_party/re2" ]
   }
diff --git a/ui/base/cocoa/remote_accessibility_api.h b/ui/base/cocoa/remote_accessibility_api.h
index 3182458838aa96d34911280ab4c6c3aa4aa22d6d..6dc85c366b7e61c8bd0302e501c3223a19223313 100644
--- a/ui/base/cocoa/remote_accessibility_api.h
+++ b/ui/base/cocoa/remote_accessibility_api.h
@@ -10,9 +10,12 @@
 #include <vector>
 
 #include "base/component_export.h"
+#include "electron/mas.h"
 
 // NSAccessibilityRemoteUIElement is a private class in AppKit.
 
+#if !IS_MAS_BUILD()
+
 @interface NSAccessibilityRemoteUIElement : NSObject
 + (void)setRemoteUIApp:(BOOL)flag;
 + (BOOL)isRemoteUIApp;
@@ -38,4 +41,6 @@ class COMPONENT_EXPORT(UI_BASE) RemoteAccessibility {
 
 }  // namespace ui
 
+#endif  // MAS_BUILD
+
 #endif  // UI_BASE_COCOA_REMOTE_ACCESSIBILITY_API_H_
diff --git a/ui/base/cocoa/remote_layer_api.h b/ui/base/cocoa/remote_layer_api.h
index 59dc2f82214cfd883b6ebef3b0fb25af6387a9cd..912c5252d1b30d943a1552739b9eef9a8eae2d7a 100644
--- a/ui/base/cocoa/remote_layer_api.h
+++ b/ui/base/cocoa/remote_layer_api.h
@@ -9,6 +9,7 @@
 
 #include "base/component_export.h"
 #include "build/build_config.h"
+#include "electron/mas.h"
 
 #if defined(__OBJC__)
 #import <Foundation/Foundation.h>
@@ -17,6 +18,7 @@
 
 #if BUILDFLAG(IS_MAC)
 
+#if !IS_MAS_BUILD()
 // The CGSConnectionID is used to create the CAContext in the process that is
 // going to share the CALayers that it is rendering to another process to
 // display.
@@ -68,6 +70,8 @@ extern NSString* const kCAContextIgnoresHitTest;
 
 #endif  // __OBJC__
 
+#endif // MAS_BUILD
+
 namespace ui {
 
 // This function will check if all of the interfaces listed above are supported
diff --git a/ui/base/cocoa/remote_layer_api.mm b/ui/base/cocoa/remote_layer_api.mm
index 93e90c4eba9bc9b93d68e834eb6baabeb2d0ecf0..1b90f41d05f847a94adf2f4da827b1d0143b7bcf 100644
--- a/ui/base/cocoa/remote_layer_api.mm
+++ b/ui/base/cocoa/remote_layer_api.mm
@@ -5,18 +5,22 @@
 #include "ui/base/cocoa/remote_layer_api.h"
 
 #include "base/feature_list.h"
+#include "electron/mas.h"
 
 #include <objc/runtime.h>
 
 namespace ui {
 
+#if !IS_MAS_BUILD()
 namespace {
 // Control use of cross-process CALayers to display content directly from the
 // GPU process on Mac.
 BASE_FEATURE(kRemoteCoreAnimationAPI, base::FEATURE_ENABLED_BY_DEFAULT);
 }  // namespace
+#endif
 
 bool RemoteLayerAPISupported() {
+#if !IS_MAS_BUILD()
   if (!base::FeatureList::IsEnabled(kRemoteCoreAnimationAPI))
     return false;
 
@@ -53,6 +57,9 @@ bool RemoteLayerAPISupported() {
 
   // If everything is there, we should be able to use the API.
   return true;
+#else
+  return false;
+#endif  // MAS_BUILD
 }
 
 }  // namespace
diff --git a/ui/display/BUILD.gn b/ui/display/BUILD.gn
index 41572ec01d71f56eb8815cf9845e2c4ccefb9964..90c72f19b557d985581c7250187616ee85821964 100644
--- a/ui/display/BUILD.gn
+++ b/ui/display/BUILD.gn
@@ -132,6 +132,12 @@ component("display") {
     "//ui/gfx/geometry",
   ]
 
+  if (is_mac) {
+    deps += [
+      "//electron/build/config:generate_mas_config"
+    ]
+  }
+
   if (is_ios) {
     deps += [ "//build:ios_buildflags" ]
   }
diff --git a/ui/display/mac/screen_mac.mm b/ui/display/mac/screen_mac.mm
index 890d86acb0e92760590b4d0860dd41eaa70486c7..2e9e16cb47606f627b1473a479a6e8ae514cb88e 100644
--- a/ui/display/mac/screen_mac.mm
+++ b/ui/display/mac/screen_mac.mm
@@ -29,6 +29,7 @@
 #include "build/build_config.h"
 #include "components/device_event_log/device_event_log.h"
 #include "components/viz/common/resources/shared_image_format.h"
+#include "electron/mas.h"
 #include "ui/display/display.h"
 #include "ui/display/display_change_notifier.h"
 #include "ui/display/mac/screen_mac_headless.h"
@@ -179,7 +180,17 @@ DisplayMac BuildDisplayForScreen(NSScreen* screen) {
     display.set_color_depth(Display::kDefaultBitsPerPixel);
     display.set_depth_per_component(Display::kDefaultBitsPerComponent);
   }
+#if IS_MAS_BUILD()
+  // This is equivalent to the CGDisplayUsesForceToGray() API as at 2018-08-06,
+  // but avoids usage of the private API.
+  CFStringRef app = CFSTR("com.apple.CoreGraphics");
+  CFStringRef key = CFSTR("DisplayUseForcedGray");
+  Boolean key_valid = false;
+  display.set_is_monochrome(
+      CFPreferencesGetAppBooleanValue(key, app, &key_valid));
+#else
   display.set_is_monochrome(CGDisplayUsesForceToGray());
+#endif
 
   // Query the display's refresh rate.
   double refresh_rate = 1.0 / screen.minimumRefreshInterval;
diff --git a/ui/gfx/BUILD.gn b/ui/gfx/BUILD.gn
index f29089286f4848400a67c3b7eaf21a1ba291cc1e..fa92acfa219f82cf53207e3a7479e44b223e9050 100644
--- a/ui/gfx/BUILD.gn
+++ b/ui/gfx/BUILD.gn
@@ -333,6 +333,12 @@ component("gfx") {
     "//ui/base:ui_data_pack",
   ]
 
+  if (is_mac) {
+    deps += [
+      "//electron/build/config:generate_mas_config"
+    ]
+  }
+
   if (!is_apple) {
     sources += [
       "platform_font_skia.cc",
diff --git a/ui/gfx/platform_font_mac.mm b/ui/gfx/platform_font_mac.mm
index bbe355cf69f160866188216cc274d75bd35603db..06ee100d7ea2e892dbf3c0b1adc96c5013ef678a 100644
--- a/ui/gfx/platform_font_mac.mm
+++ b/ui/gfx/platform_font_mac.mm
@@ -19,6 +19,7 @@
 #include "base/numerics/safe_conversions.h"
 #include "base/strings/sys_string_conversions.h"
 #include "base/strings/utf_string_conversions.h"
+#include "electron/mas.h"
 #include "third_party/skia/include/ports/SkTypeface_mac.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/font.h"
@@ -28,9 +29,11 @@
 
 using Weight = Font::Weight;
 
+#if !IS_MAS_BUILD()
 extern "C" {
 bool CTFontDescriptorIsSystemUIFont(CTFontDescriptorRef);
 }
+#endif
 
 namespace {
 
@@ -250,7 +253,13 @@ CTFontRef SystemFontForConstructorOfType(
   // TODO(avi, etienneb): Figure out this font stuff.
   base::apple::ScopedCFTypeRef<CTFontDescriptorRef> descriptor(
       CTFontCopyFontDescriptor(font));
+#if IS_MAS_BUILD()
+  CFNumberRef priority = (CFNumberRef)CTFontDescriptorCopyAttribute(descriptor.get(), (CFStringRef)kCTFontPriorityAttribute);
+  SInt64 v;
+  if (CFNumberGetValue(priority, kCFNumberSInt64Type, &v) && v == kCTFontPrioritySystem) {
+#else
   if (CTFontDescriptorIsSystemUIFont(descriptor.get())) {
+#endif
     // Assume it's the standard system font. The fact that this much is known is
     // enough.
     return PlatformFontMac::SystemFontType::kGeneral;
diff --git a/ui/views/BUILD.gn b/ui/views/BUILD.gn
index becf47ac859e2ea5d68d449010606bc787606239..45f13c71703bc2e67aa668b8360f555f592c9555 100644
--- a/ui/views/BUILD.gn
+++ b/ui/views/BUILD.gn
@@ -723,6 +723,8 @@ component("views") {
       "IOSurface.framework",
       "QuartzCore.framework",
     ]
+
+    deps += ["//electron/build/config:generate_mas_config"]
   }
 
   if (is_win) {
@@ -1153,6 +1155,8 @@ source_set("test_support") {
     "//ui/base/mojom:ui_base_types",
   ]
 
+  deps += ["//electron/build/config:generate_mas_config"]
+
   if (is_win) {
     sources += [
       "test/desktop_window_tree_host_win_test_api.cc",
diff --git a/ui/views/cocoa/native_widget_mac_ns_window_host.h b/ui/views/cocoa/native_widget_mac_ns_window_host.h
index fdc7eb4e4c5e8338c725f7d317559b091d8b38fe..2239b085ac7fd87fe06aef1001551f8afe8e21e4 100644
--- a/ui/views/cocoa/native_widget_mac_ns_window_host.h
+++ b/ui/views/cocoa/native_widget_mac_ns_window_host.h
@@ -19,6 +19,7 @@
 #include "components/remote_cocoa/browser/scoped_cg_window_id.h"
 #include "components/remote_cocoa/common/native_widget_ns_window.mojom.h"
 #include "components/remote_cocoa/common/native_widget_ns_window_host.mojom.h"
+#include "electron/mas.h"
 #include "mojo/public/cpp/bindings/associated_receiver.h"
 #include "mojo/public/cpp/bindings/associated_remote.h"
 #include "ui/accelerated_widget_mac/accelerated_widget_mac.h"
@@ -34,7 +35,9 @@
 #include "ui/views/window/dialog_observer.h"
 
 @class NativeWidgetMacNSWindow;
+#if !IS_MAS_BUILD()
 @class NSAccessibilityRemoteUIElement;
+#endif
 @class NSView;
 
 namespace remote_cocoa {
@@ -506,10 +509,12 @@ class VIEWS_EXPORT NativeWidgetMacNSWindowHost
   mojo::AssociatedRemote<remote_cocoa::mojom::NativeWidgetNSWindow>
       remote_ns_window_remote_;
 
+#if !IS_MAS_BUILD()
   // Remote accessibility objects corresponding to the NSWindow and its root
   // NSView.
   NSAccessibilityRemoteUIElement* __strong remote_window_accessible_;
   NSAccessibilityRemoteUIElement* __strong remote_view_accessible_;
+#endif
 
   // Used to force the NSApplication's focused accessibility element to be the
   // views::Views accessibility tree when the NSView for this is focused.
diff --git a/ui/views/cocoa/native_widget_mac_ns_window_host.mm b/ui/views/cocoa/native_widget_mac_ns_window_host.mm
index 5c0d4134c8205b018a4f71509879485a7f92bcf2..d2204fd2b737f7f3e146cb1be80c3be6bfce8cd4 100644
--- a/ui/views/cocoa/native_widget_mac_ns_window_host.mm
+++ b/ui/views/cocoa/native_widget_mac_ns_window_host.mm
@@ -21,6 +21,7 @@
 #include "components/remote_cocoa/app_shim/native_widget_ns_window_bridge.h"
 #include "components/remote_cocoa/browser/ns_view_ids.h"
 #include "components/remote_cocoa/browser/window.h"
+#include "electron/mas.h"
 #include "mojo/public/cpp/bindings/self_owned_associated_receiver.h"
 #include "ui/accelerated_widget_mac/window_resize_helper_mac.h"
 #include "ui/accessibility/accessibility_features.h"
@@ -362,8 +363,12 @@ void HandleAccelerator(const ui::Accelerator& accelerator,
   if (in_process_ns_window_bridge_) {
     return gfx::NativeViewAccessible(in_process_ns_window_bridge_->ns_view());
   }
+#if !IS_MAS_BUILD()
   return gfx::NativeViewAccessible(
       (id<NSAccessibility>)remote_view_accessible_);
+#else
+  return {};
+#endif
 }
 
 gfx::NativeViewAccessible
@@ -379,8 +384,12 @@ void HandleAccelerator(const ui::Accelerator& accelerator,
         [in_process_ns_window_bridge_->ns_view() window]);
   }
 
+#if !IS_MAS_BUILD()
   return gfx::NativeViewAccessible(
       (id<NSAccessibility>)remote_window_accessible_);
+#else
+  return {};
+#endif
 }
 
 remote_cocoa::mojom::NativeWidgetNSWindow*
@@ -1451,9 +1460,11 @@ void HandleAccelerator(const ui::Accelerator& accelerator,
   // for PWAs. However this breaks accessibility on in-process windows,
   // so set it back to NO when a local window gains focus. See
   // https://crbug.com/41485830.
+#if !IS_MAS_BUILD()
   if (is_key && features::IsAccessibilityRemoteUIAppEnabled()) {
     [NSAccessibilityRemoteUIElement setRemoteUIApp:!!application_host_];
   }
+#endif
   // Explicitly set the keyboard accessibility state on regaining key
   // window status.
   if (is_key && is_content_first_responder) {
@@ -1606,17 +1617,20 @@ void HandleAccelerator(const ui::Accelerator& accelerator,
 void NativeWidgetMacNSWindowHost::SetRemoteAccessibilityTokens(
     const std::vector<uint8_t>& window_token,
     const std::vector<uint8_t>& view_token) {
+#if !IS_MAS_BUILD()
   remote_window_accessible_ =
       ui::RemoteAccessibility::GetRemoteElementFromToken(window_token);
   remote_view_accessible_ =
       ui::RemoteAccessibility::GetRemoteElementFromToken(view_token);
   [remote_view_accessible_ setWindowUIElement:remote_window_accessible_];
   [remote_view_accessible_ setTopLevelUIElement:remote_window_accessible_];
+#endif
 }
 
 bool NativeWidgetMacNSWindowHost::GetRootViewAccessibilityToken(
     base::ProcessId* pid,
     std::vector<uint8_t>* token) {
+#if !IS_MAS_BUILD()
   *pid = getpid();
   id element_id = GetNativeViewAccessible();
 
@@ -1629,6 +1643,7 @@ void HandleAccelerator(const ui::Accelerator& accelerator,
   }
 
   *token = ui::RemoteAccessibility::GetTokenForLocalElement(element_id);
+#endif
   return true;
 }
 
diff --git a/ui/views/controls/webview/BUILD.gn b/ui/views/controls/webview/BUILD.gn
index 50bb38a38dca67f9f393c48efe123f7dd7ca2594..2062e479581d63325de3c3398844acca0601c86c 100644
--- a/ui/views/controls/webview/BUILD.gn
+++ b/ui/views/controls/webview/BUILD.gn
@@ -46,6 +46,12 @@ component("webview") {
     "//url",
   ]
 
+  if (is_mac) {
+    deps += [
+      "//electron/build/config:generate_mas_config",
+    ]
+  }
+
   public_deps = [
     "//base",
     "//content/public/browser",