electron/patches/chromium/feat_offscreen_rendering_with_viz_compositor.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Heilig Benedek <benecene@gmail.com>
Date: Wed, 20 Mar 2019 20:30:44 +0100
Subject: feat_offscreen_rendering_with_viz_compositor.patch


diff --git a/components/viz/host/host_display_client.cc b/components/viz/host/host_display_client.cc
index f5e18df4e06e24d3bdd51308abde48e217444848..41017d9d53b1c0d563ea0901f5cae407c6cf1560 100644
--- a/components/viz/host/host_display_client.cc
+++ b/components/viz/host/host_display_client.cc
@@ -18,6 +18,10 @@
 
 namespace viz {
 
+void HostDisplayClient::IsOffscreen(IsOffscreenCallback callback) {
+  std::move(callback).Run(false);
+}
+
 HostDisplayClient::HostDisplayClient(gfx::AcceleratedWidget widget)
     : binding_(this) {
 #if defined(OS_MACOSX) || defined(OS_WIN)
@@ -46,9 +50,9 @@ void HostDisplayClient::OnDisplayReceivedCALayerParams(
 }
 #endif
 
-#if defined(OS_WIN)
 void HostDisplayClient::CreateLayeredWindowUpdater(
     mojom::LayeredWindowUpdaterRequest request) {
+#if defined(OS_WIN)
   if (!NeedsToUseLayerWindow(widget_)) {
     DLOG(ERROR) << "HWND shouldn't be using a layered window";
     return;
@@ -56,8 +60,12 @@ void HostDisplayClient::CreateLayeredWindowUpdater(
 
   layered_window_updater_ =
       std::make_unique<LayeredWindowUpdaterImpl>(widget_, std::move(request));
-}
+#else
+  CHECK(false) << "Chromium is calling CreateLayeredWindowUpdater for non-OSR "
+                  "windows on POSIX platforms, something is wrong with "
+                  "Electron's OSR implementation.";
 #endif
+}
 
 #if defined(USE_X11)
 void HostDisplayClient::DidCompleteSwapWithNewSize(const gfx::Size& size) {
diff --git a/components/viz/host/host_display_client.h b/components/viz/host/host_display_client.h
index b8177277ebca471fc147f2d5b53521cbadd8fa2d..72a807e138f80b4ab37cb1d368bc968e299d903f 100644
--- a/components/viz/host/host_display_client.h
+++ b/components/viz/host/host_display_client.h
@@ -30,17 +30,17 @@ class VIZ_HOST_EXPORT HostDisplayClient : public mojom::DisplayClient {
   mojom::DisplayClientPtr GetBoundPtr(
       scoped_refptr<base::SingleThreadTaskRunner> task_runner);
 
- private:
+ protected:
   // mojom::DisplayClient implementation:
 #if defined(OS_MACOSX)
   void OnDisplayReceivedCALayerParams(
       const gfx::CALayerParams& ca_layer_params) override;
 #endif
 
-#if defined(OS_WIN)
+  void IsOffscreen(IsOffscreenCallback callback) override;
+
   void CreateLayeredWindowUpdater(
       mojom::LayeredWindowUpdaterRequest request) override;
-#endif
 
 #if defined(USE_X11)
   void DidCompleteSwapWithNewSize(const gfx::Size& size) override;
diff --git a/components/viz/host/layered_window_updater_impl.cc b/components/viz/host/layered_window_updater_impl.cc
index 65c26e2f7ae813e50f6740f73a4d145467da4366..39c04c4d6b644a4ad7b13b4e932b085fad0b8293 100644
--- a/components/viz/host/layered_window_updater_impl.cc
+++ b/components/viz/host/layered_window_updater_impl.cc
@@ -43,7 +43,9 @@ void LayeredWindowUpdaterImpl::OnAllocatedSharedMemory(
   // |region|'s handle will close when it goes out of scope.
 }
 
-void LayeredWindowUpdaterImpl::Draw(DrawCallback draw_callback) {
+void LayeredWindowUpdaterImpl::Draw(
+    const gfx::Rect& damage_rect,
+    DrawCallback draw_callback) {
   TRACE_EVENT0("viz", "LayeredWindowUpdaterImpl::Draw");
 
   if (!canvas_) {
diff --git a/components/viz/host/layered_window_updater_impl.h b/components/viz/host/layered_window_updater_impl.h
index ced30727ab67e557265c3a61f7c213763da973ce..f422786fe6cd9cab47494fe6028f3c3be8bc763e 100644
--- a/components/viz/host/layered_window_updater_impl.h
+++ b/components/viz/host/layered_window_updater_impl.h
@@ -33,7 +33,7 @@ class VIZ_HOST_EXPORT LayeredWindowUpdaterImpl
   // mojom::LayeredWindowUpdater implementation.
   void OnAllocatedSharedMemory(const gfx::Size& pixel_size,
                                base::UnsafeSharedMemoryRegion region) override;
-  void Draw(DrawCallback draw_callback) override;
+  void Draw(const gfx::Rect& damage_rect, DrawCallback draw_callback) override;
 
  private:
   const HWND hwnd_;
diff --git a/components/viz/service/BUILD.gn b/components/viz/service/BUILD.gn
index a3fc1b3bdc9c22f4ac4b1ae8ddd992f419d04d55..0da7bf23e0f5309887c9038a14c33d2d80095d0b 100644
--- a/components/viz/service/BUILD.gn
+++ b/components/viz/service/BUILD.gn
@@ -118,6 +118,8 @@ viz_component("service") {
     "display_embedder/output_surface_provider_impl.h",
     "display_embedder/server_shared_bitmap_manager.cc",
     "display_embedder/server_shared_bitmap_manager.h",
+    "display_embedder/software_output_device_proxy.cc",
+    "display_embedder/software_output_device_proxy.h",
     "display_embedder/software_output_surface.cc",
     "display_embedder/software_output_surface.h",
     "display_embedder/viz_process_context_provider.cc",
diff --git a/components/viz/service/display_embedder/output_surface_provider_impl.cc b/components/viz/service/display_embedder/output_surface_provider_impl.cc
index e3c8e9dbca69f2665e8dbbd798d45c3b7199e04c..d9fa2d536e977ac966065a9058661f887e995320 100644
--- a/components/viz/service/display_embedder/output_surface_provider_impl.cc
+++ b/components/viz/service/display_embedder/output_surface_provider_impl.cc
@@ -20,6 +20,7 @@
 #include "components/viz/service/display_embedder/server_shared_bitmap_manager.h"
 #include "components/viz/service/display_embedder/skia_output_surface_dependency_impl.h"
 #include "components/viz/service/display_embedder/skia_output_surface_impl.h"
+#include "components/viz/service/display_embedder/software_output_device_proxy.h"
 #include "components/viz/service/display_embedder/software_output_surface.h"
 #include "components/viz/service/display_embedder/viz_process_context_provider.h"
 #include "components/viz/service/gl/gpu_service_impl.h"
@@ -33,6 +34,7 @@
 #include "gpu/ipc/scheduler_sequence.h"
 #include "gpu/ipc/service/gpu_channel_manager_delegate.h"
 #include "gpu/ipc/service/image_transport_surface.h"
+#include "services/viz/privileged/mojom/compositing/layered_window_updater.mojom.h"
 #include "ui/base/ui_base_switches.h"
 #include "ui/gl/gl_context.h"
 #include "ui/gl/init/gl_factory.h"
@@ -223,6 +225,19 @@ OutputSurfaceProviderImpl::CreateSoftwareOutputDeviceForPlatform(
   if (headless_)
     return std::make_unique<SoftwareOutputDevice>();
 
+#if !defined(OS_MACOSX)
+  DCHECK(display_client);
+  bool offscreen = false;
+  if (display_client->IsOffscreen(&offscreen) && offscreen) {
+    mojom::LayeredWindowUpdaterPtr layered_window_updater;
+    display_client->CreateLayeredWindowUpdater(
+        mojo::MakeRequest(&layered_window_updater));
+
+    return std::make_unique<SoftwareOutputDeviceProxy>(
+        std::move(layered_window_updater));
+  }
+#endif
+
 #if defined(OS_WIN)
   return CreateSoftwareOutputDeviceWin(surface_handle, &output_device_backing_,
                                        display_client);
diff --git a/components/viz/service/display_embedder/software_output_device_mac.cc b/components/viz/service/display_embedder/software_output_device_mac.cc
index b9357082293cc55650144ccbc8bada8fe6d1cac4..b4cb07e26d1504719f80e5835c1cb5f138b9f1ab 100644
--- a/components/viz/service/display_embedder/software_output_device_mac.cc
+++ b/components/viz/service/display_embedder/software_output_device_mac.cc
@@ -102,6 +102,8 @@ void SoftwareOutputDeviceMac::UpdateAndCopyBufferDamage(
 
 SkCanvas* SoftwareOutputDeviceMac::BeginPaint(
     const gfx::Rect& new_damage_rect) {
+  last_damage = new_damage_rect;
+
   // Record the previous paint buffer.
   Buffer* previous_paint_buffer =
       buffer_queue_.empty() ? nullptr : buffer_queue_.back().get();
@@ -184,6 +186,7 @@ void SoftwareOutputDeviceMac::EndPaint() {
     ca_layer_params.is_empty = false;
     ca_layer_params.scale_factor = scale_factor_;
     ca_layer_params.pixel_size = pixel_size_;
+    ca_layer_params.damage = last_damage;
     ca_layer_params.io_surface_mach_port.reset(
         IOSurfaceCreateMachPort(current_paint_buffer_->io_surface));
     client_->SoftwareDeviceUpdatedCALayerParams(ca_layer_params);
diff --git a/components/viz/service/display_embedder/software_output_device_mac.h b/components/viz/service/display_embedder/software_output_device_mac.h
index f3867356e3d641416e00e6d115ae9ae2a0be90ab..b1d192d2b20ccb63fba07093101d745e5ffe86dd 100644
--- a/components/viz/service/display_embedder/software_output_device_mac.h
+++ b/components/viz/service/display_embedder/software_output_device_mac.h
@@ -56,6 +56,7 @@ class VIZ_SERVICE_EXPORT SoftwareOutputDeviceMac : public SoftwareOutputDevice {
   void UpdateAndCopyBufferDamage(Buffer* previous_paint_buffer,
                                  const SkRegion& new_damage_rect);
 
+  gfx::Rect last_damage;
   gfx::Size pixel_size_;
   float scale_factor_ = 1;
 
diff --git a/components/viz/service/display_embedder/software_output_device_proxy.cc b/components/viz/service/display_embedder/software_output_device_proxy.cc
new file mode 100644
index 0000000000000000000000000000000000000000..c17b03e00089bfd301c63910426bb16afb8cdae7
--- /dev/null
+++ b/components/viz/service/display_embedder/software_output_device_proxy.cc
@@ -0,0 +1,156 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "components/viz/service/display_embedder/software_output_device_proxy.h"
+
+#include "base/memory/unsafe_shared_memory_region.h"
+#include "base/threading/thread_checker.h"
+#include "components/viz/common/resources/resource_sizes.h"
+#include "components/viz/service/display_embedder/output_device_backing.h"
+#include "mojo/public/cpp/system/platform_handle.h"
+#include "services/viz/privileged/mojom/compositing/layered_window_updater.mojom.h"
+#include "skia/ext/platform_canvas.h"
+#include "third_party/skia/include/core/SkCanvas.h"
+#include "ui/gfx/skia_util.h"
+
+#if defined(OS_WIN)
+#include "skia/ext/skia_utils_win.h"
+#include "ui/gfx/gdi_util.h"
+#include "ui/gfx/win/hwnd_util.h"
+#else
+#include "mojo/public/cpp/base/shared_memory_utils.h"
+#endif
+
+namespace viz {
+
+SoftwareOutputDeviceBase::~SoftwareOutputDeviceBase() {
+  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
+  DCHECK(!in_paint_);
+}
+
+void SoftwareOutputDeviceBase::Resize(const gfx::Size& viewport_pixel_size,
+                                         float scale_factor) {
+  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
+  DCHECK(!in_paint_);
+
+  if (viewport_pixel_size_ == viewport_pixel_size)
+    return;
+
+  viewport_pixel_size_ = viewport_pixel_size;
+  ResizeDelegated();
+}
+
+SkCanvas* SoftwareOutputDeviceBase::BeginPaint(
+    const gfx::Rect& damage_rect) {
+  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
+  DCHECK(!in_paint_);
+
+  damage_rect_ = damage_rect;
+  in_paint_ = true;
+  return BeginPaintDelegated();
+}
+
+void SoftwareOutputDeviceBase::EndPaint() {
+  DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
+  DCHECK(in_paint_);
+
+  in_paint_ = false;
+
+  gfx::Rect intersected_damage_rect = damage_rect_;
+  intersected_damage_rect.Intersect(gfx::Rect(viewport_pixel_size_));
+  if (intersected_damage_rect.IsEmpty())
+    return;
+
+  EndPaintDelegated(intersected_damage_rect);
+}
+
+SoftwareOutputDeviceProxy::~SoftwareOutputDeviceProxy() = default;
+
+SoftwareOutputDeviceProxy::SoftwareOutputDeviceProxy(
+    mojom::LayeredWindowUpdaterPtr layered_window_updater)
+    : layered_window_updater_(std::move(layered_window_updater)) {
+  DCHECK(layered_window_updater_.is_bound());
+}
+
+void SoftwareOutputDeviceProxy::OnSwapBuffers(
+    SoftwareOutputDevice::SwapBuffersCallback swap_ack_callback) {
+  DCHECK(swap_ack_callback_.is_null());
+
+  // We aren't waiting on DrawAck() and can immediately run the callback.
+  if (!waiting_on_draw_ack_) {
+    task_runner_->PostTask(FROM_HERE,
+        base::BindOnce(std::move(swap_ack_callback), viewport_pixel_size_));
+    return;
+  }
+
+  swap_ack_callback_ = std::move(swap_ack_callback);
+}
+
+void SoftwareOutputDeviceProxy::ResizeDelegated() {
+  canvas_.reset();
+
+  size_t required_bytes;
+  if (!ResourceSizes::MaybeSizeInBytes(
+          viewport_pixel_size_, ResourceFormat::RGBA_8888, &required_bytes)) {
+    DLOG(ERROR) << "Invalid viewport size " << viewport_pixel_size_.ToString();
+    return;
+  }
+
+  base::UnsafeSharedMemoryRegion region =
+      base::UnsafeSharedMemoryRegion::Create(required_bytes);
+  if (!region.IsValid()) {
+    DLOG(ERROR) << "Failed to allocate " << required_bytes << " bytes";
+    return;
+  }
+
+  #if defined(WIN32)
+  canvas_ = skia::CreatePlatformCanvasWithSharedSection(
+      viewport_pixel_size_.width(), viewport_pixel_size_.height(), false,
+      region.GetPlatformHandle(), skia::CRASH_ON_FAILURE);
+  #else
+  shm_mapping_ = region.Map();
+  if (!shm_mapping_.IsValid()) {
+    DLOG(ERROR) << "Failed to map " << required_bytes << " bytes";
+    return;
+  }
+
+  canvas_ = skia::CreatePlatformCanvasWithPixels(
+      viewport_pixel_size_.width(), viewport_pixel_size_.height(), false,
+      static_cast<uint8_t*>(shm_mapping_.memory()), skia::CRASH_ON_FAILURE);
+  #endif
+
+  // Transfer region ownership to the browser process.
+  layered_window_updater_->OnAllocatedSharedMemory(viewport_pixel_size_,
+                                                   std::move(region));
+}
+
+SkCanvas* SoftwareOutputDeviceProxy::BeginPaintDelegated() {
+  return canvas_.get();
+}
+
+void SoftwareOutputDeviceProxy::EndPaintDelegated(
+    const gfx::Rect& damage_rect) {
+  DCHECK(!waiting_on_draw_ack_);
+
+  if (!canvas_)
+    return;
+
+  layered_window_updater_->Draw(damage_rect, base::BindOnce(
+      &SoftwareOutputDeviceProxy::DrawAck, base::Unretained(this)));
+  waiting_on_draw_ack_ = true;
+
+  TRACE_EVENT_ASYNC_BEGIN0("viz", "SoftwareOutputDeviceProxy::Draw", this);
+}
+
+void SoftwareOutputDeviceProxy::DrawAck() {
+  DCHECK(waiting_on_draw_ack_);
+  DCHECK(!swap_ack_callback_.is_null());
+
+  TRACE_EVENT_ASYNC_END0("viz", "SoftwareOutputDeviceProxy::Draw", this);
+
+  waiting_on_draw_ack_ = false;
+  std::move(swap_ack_callback_).Run(viewport_pixel_size_);
+}
+
+}  // namespace viz
diff --git a/components/viz/service/display_embedder/software_output_device_proxy.h b/components/viz/service/display_embedder/software_output_device_proxy.h
new file mode 100644
index 0000000000000000000000000000000000000000..3865939d0445a23a468770f57207ba5ef23277ed
--- /dev/null
+++ b/components/viz/service/display_embedder/software_output_device_proxy.h
@@ -0,0 +1,88 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef COMPONENTS_VIZ_SERVICE_DISPLAY_EMBEDDER_SOFTWARE_OUTPUT_DEVICE_PROXY_H_
+#define COMPONENTS_VIZ_SERVICE_DISPLAY_EMBEDDER_SOFTWARE_OUTPUT_DEVICE_PROXY_H_
+
+#if defined(OS_WIN)
+#include <windows.h>
+#endif
+
+#include <memory>
+
+#include "components/viz/host/host_display_client.h"
+#include "components/viz/service/display/software_output_device.h"
+#include "components/viz/service/viz_service_export.h"
+#include "services/viz/privileged/mojom/compositing/display_private.mojom.h"
+#include "services/viz/privileged/mojom/compositing/layered_window_updater.mojom.h"
+
+namespace viz {
+
+// Shared base class for SoftwareOutputDevice implementations.
+class SoftwareOutputDeviceBase : public SoftwareOutputDevice {
+ public:
+  SoftwareOutputDeviceBase() = default;
+  ~SoftwareOutputDeviceBase() override;
+
+  // SoftwareOutputDevice implementation.
+  void Resize(const gfx::Size& viewport_pixel_size,
+              float scale_factor) override;
+  SkCanvas* BeginPaint(const gfx::Rect& damage_rect) override;
+  void EndPaint() override;
+
+  // Called from Resize() if |viewport_pixel_size_| has changed.
+  virtual void ResizeDelegated() = 0;
+
+  // Called from BeginPaint() and should return an SkCanvas.
+  virtual SkCanvas* BeginPaintDelegated() = 0;
+
+  // Called from EndPaint() if there is damage.
+  virtual void EndPaintDelegated(const gfx::Rect& damage_rect) = 0;
+
+ private:
+  bool in_paint_ = false;
+
+  THREAD_CHECKER(thread_checker_);
+
+  DISALLOW_COPY_AND_ASSIGN(SoftwareOutputDeviceBase);
+};
+
+// SoftwareOutputDevice implementation that draws indirectly. An implementation
+// of mojom::LayeredWindowUpdater in the browser process handles the actual
+// drawing. Pixel backing is in SharedMemory so no copying between processes
+// is required.
+class SoftwareOutputDeviceProxy : public SoftwareOutputDeviceBase {
+ public:
+  explicit SoftwareOutputDeviceProxy(
+      mojom::LayeredWindowUpdaterPtr layered_window_updater);
+  ~SoftwareOutputDeviceProxy() override;
+
+  // SoftwareOutputDevice implementation.
+  void OnSwapBuffers(SoftwareOutputDevice::SwapBuffersCallback swap_ack_callback) override;
+
+  // SoftwareOutputDeviceBase implementation.
+  void ResizeDelegated() override;
+  SkCanvas* BeginPaintDelegated() override;
+  void EndPaintDelegated(const gfx::Rect& rect) override;
+
+ private:
+  // Runs |swap_ack_callback_| after draw has happened.
+  void DrawAck();
+
+  mojom::LayeredWindowUpdaterPtr layered_window_updater_;
+
+  std::unique_ptr<SkCanvas> canvas_;
+  bool waiting_on_draw_ack_ = false;
+  SoftwareOutputDevice::SwapBuffersCallback swap_ack_callback_;
+
+#if !defined(WIN32)
+  base::WritableSharedMemoryMapping shm_mapping_;
+#endif
+
+  DISALLOW_COPY_AND_ASSIGN(SoftwareOutputDeviceProxy);
+};
+
+}  // namespace viz
+
+#endif  // COMPONENTS_VIZ_SERVICE_DISPLAY_EMBEDDER_SOFTWARE_OUTPUT_DEVICE_PROXY_H_
diff --git a/components/viz/service/display_embedder/software_output_device_win.cc b/components/viz/service/display_embedder/software_output_device_win.cc
index 74316edc0e0bd28b1772e9d7cf34327d113462c4..9cbe5400458ce6e0b8ea9edfa3f0969fb936ee1e 100644
--- a/components/viz/service/display_embedder/software_output_device_win.cc
+++ b/components/viz/service/display_embedder/software_output_device_win.cc
@@ -11,6 +11,7 @@
 #include "components/viz/common/display/use_layered_window.h"
 #include "components/viz/common/resources/resource_sizes.h"
 #include "components/viz/service/display_embedder/output_device_backing.h"
+#include "components/viz/service/display_embedder/software_output_device_proxy.h"
 #include "mojo/public/cpp/system/platform_handle.h"
 #include "services/viz/privileged/mojom/compositing/layered_window_updater.mojom.h"
 #include "skia/ext/platform_canvas.h"
@@ -265,7 +266,7 @@ void SoftwareOutputDeviceWinProxy::EndPaintDelegated(
   if (!canvas_)
     return;
 
-  layered_window_updater_->Draw(base::BindOnce(
+  layered_window_updater_->Draw(damage_rect, base::BindOnce(
       &SoftwareOutputDeviceWinProxy::DrawAck, base::Unretained(this)));
   waiting_on_draw_ack_ = true;
 
@@ -297,8 +298,13 @@ std::unique_ptr<SoftwareOutputDevice> CreateSoftwareOutputDeviceWin(
     display_client->CreateLayeredWindowUpdater(
         mojo::MakeRequest(&layered_window_updater));
 
-    return std::make_unique<SoftwareOutputDeviceWinProxy>(
-        hwnd, std::move(layered_window_updater));
+    bool offscreen = false;
+    if (display_client->IsOffscreen(&offscreen) && offscreen)
+      return std::make_unique<SoftwareOutputDeviceProxy>(
+          std::move(layered_window_updater));
+    else
+      return std::make_unique<SoftwareOutputDeviceWinProxy>(
+          hwnd, std::move(layered_window_updater));
   } else {
     return std::make_unique<SoftwareOutputDeviceWinDirect>(hwnd, backing);
   }
diff --git a/services/viz/privileged/mojom/compositing/display_private.mojom b/services/viz/privileged/mojom/compositing/display_private.mojom
index 5c6292cfb3b8b46802c772d202d19c78e4782488..ed27af3ab0b383553b4d9492d29cec2b91bee807 100644
--- a/services/viz/privileged/mojom/compositing/display_private.mojom
+++ b/services/viz/privileged/mojom/compositing/display_private.mojom
@@ -79,12 +79,14 @@ interface DisplayPrivate {
 };
 
 interface DisplayClient {
+  [Sync]
+  IsOffscreen() => (bool success);
+
   [EnableIf=is_mac]
   OnDisplayReceivedCALayerParams(gfx.mojom.CALayerParams ca_layer_params);
 
   // Creates a LayeredWindowUpdater implementation to draw into a layered
   // window.
-  [EnableIf=is_win]
   CreateLayeredWindowUpdater(LayeredWindowUpdater& layered_window_updater);
 
   // Notifies that a swap has occurred and provides information about the pixel
diff --git a/services/viz/privileged/mojom/compositing/layered_window_updater.mojom b/services/viz/privileged/mojom/compositing/layered_window_updater.mojom
index 6b7fbb6cf13dc8ee6ade0878a9a2c1efc5d4d3f1..e2af75168cb914a7b3b4a6c9b6a285498c3f8e72 100644
--- a/services/viz/privileged/mojom/compositing/layered_window_updater.mojom
+++ b/services/viz/privileged/mojom/compositing/layered_window_updater.mojom
@@ -26,5 +26,5 @@ interface LayeredWindowUpdater {
   // Draws to the HWND by copying pixels from shared memory. Callback must be
   // called after draw operation is complete to signal shared memory can be
   // modified.
-  Draw() => ();
+  Draw(gfx.mojom.Rect damage_rect) => ();
 };
diff --git a/ui/compositor/compositor.h b/ui/compositor/compositor.h
index ff4562c024be6bc6eb2b975b3a13c6139b89f88e..22ed4f873266143310bf5ef55df3df2a8b9aea93 100644
--- a/ui/compositor/compositor.h
+++ b/ui/compositor/compositor.h
@@ -23,6 +23,7 @@
 #include "cc/trees/layer_tree_host_single_thread_client.h"
 #include "components/viz/common/frame_sinks/begin_frame_args.h"
 #include "components/viz/common/surfaces/frame_sink_id.h"
+#include "components/viz/host/host_display_client.h"
 #include "components/viz/host/host_frame_sink_client.h"
 #include "services/viz/privileged/mojom/compositing/vsync_parameter_observer.mojom-forward.h"
 #include "third_party/skia/include/core/SkColor.h"
@@ -194,6 +195,15 @@ class COMPOSITOR_EXPORT ContextFactory {
   virtual bool SyncTokensRequiredForDisplayCompositor() = 0;
 };
 
+class COMPOSITOR_EXPORT CompositorDelegate {
+ public:
+  virtual std::unique_ptr<viz::HostDisplayClient> CreateHostDisplayClient(
+      ui::Compositor* compositor) = 0;
+
+ protected:
+  virtual ~CompositorDelegate() {}
+};
+
 // Compositor object to take care of GPU painting.
 // A Browser compositor object is responsible for generating the final
 // displayable form of pixels comprising a single widget's contents. It draws an
@@ -233,6 +243,9 @@ class COMPOSITOR_EXPORT Compositor : public cc::LayerTreeHostClient,
   // Schedules a redraw of the layer tree associated with this compositor.
   void ScheduleDraw();
 
+  CompositorDelegate* delegate() const { return delegate_; }
+  void SetDelegate(CompositorDelegate* delegate) { delegate_ = delegate; }
+
   // Sets the root of the layer tree drawn by this Compositor. The root layer
   // must have no parent. The compositor's root layer is reset if the root layer
   // is destroyed. NULL can be passed to reset the root layer, in which case the
@@ -450,6 +463,8 @@ class COMPOSITOR_EXPORT Compositor : public cc::LayerTreeHostClient,
   ui::ContextFactory* context_factory_;
   ui::ContextFactoryPrivate* context_factory_private_;
 
+  CompositorDelegate* delegate_ = nullptr;
+
   // The root of the Layer tree drawn by this compositor.
   Layer* root_layer_ = nullptr;
 
diff --git a/ui/compositor/host/host_context_factory_private.cc b/ui/compositor/host/host_context_factory_private.cc
index d32c154b965bf9fa90f8ebb2a8dd395302efc57d..f63efc91890af45c5a767bfb892ef252b22c253e 100644
--- a/ui/compositor/host/host_context_factory_private.cc
+++ b/ui/compositor/host/host_context_factory_private.cc
@@ -98,8 +98,12 @@ void HostContextFactoryPrivate::ConfigureCompositor(
       mojo::MakeRequest(&root_params->compositor_frame_sink_client);
   root_params->display_private =
       mojo::MakeRequest(&compositor_data.display_private);
-  compositor_data.display_client =
-      std::make_unique<HostDisplayClient>(compositor);
+  if (compositor->delegate())
+    compositor_data.display_client = compositor->delegate()->CreateHostDisplayClient(
+        compositor);
+  else
+    compositor_data.display_client =
+        std::make_unique<HostDisplayClient>(compositor);
   root_params->display_client =
       compositor_data.display_client->GetBoundPtr(resize_task_runner_)
           .PassInterface();
diff --git a/ui/gfx/ca_layer_params.h b/ui/gfx/ca_layer_params.h
index 4014e64a75da88cf66c02e8adb71171c2666cab7..25e57784e1a1ffc546b003daa4cd0059c468432f 100644
--- a/ui/gfx/ca_layer_params.h
+++ b/ui/gfx/ca_layer_params.h
@@ -6,6 +6,7 @@
 #define UI_GFX_CA_LAYER_PARAMS_H_
 
 #include "build/build_config.h"
+#include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/geometry/size.h"
 #include "ui/gfx/gfx_export.h"
 
@@ -41,6 +42,8 @@ struct GFX_EXPORT CALayerParams {
   gfx::ScopedRefCountedIOSurfaceMachPort io_surface_mach_port;
 #endif
 
+  gfx::Rect damage;
+
   // The geometry of the frame.
   gfx::Size pixel_size;
   float scale_factor = 1.f;
diff --git a/ui/gfx/mojom/ca_layer_params.mojom b/ui/gfx/mojom/ca_layer_params.mojom
index a73b2e678ffe0a682d0aa5409724fb441768bec5..6c36626d204c77ef51278b9e8f6fc6ee24a7a9ab 100644
--- a/ui/gfx/mojom/ca_layer_params.mojom
+++ b/ui/gfx/mojom/ca_layer_params.mojom
@@ -18,5 +18,6 @@ struct CALayerParams {
   bool is_empty;
   CALayerContent content;
   gfx.mojom.Size pixel_size;
+  gfx.mojom.Rect damage;
   float scale_factor;
 };
diff --git a/ui/gfx/mojom/ca_layer_params_mojom_traits.cc b/ui/gfx/mojom/ca_layer_params_mojom_traits.cc
index 843d5c24ec33de07c12d4417eb111f91dbcd42fe..0ea594950fcd2686f1b07248dbc8ceb257d89dca 100644
--- a/ui/gfx/mojom/ca_layer_params_mojom_traits.cc
+++ b/ui/gfx/mojom/ca_layer_params_mojom_traits.cc
@@ -52,6 +52,9 @@ bool StructTraits<gfx::mojom::CALayerParamsDataView, gfx::CALayerParams>::Read(
   if (!data.ReadPixelSize(&out->pixel_size))
     return false;
 
+  if (!data.ReadDamage(&out->damage))
+    return false;
+
   out->scale_factor = data.scale_factor();
   return true;
 }
diff --git a/ui/gfx/mojom/ca_layer_params_mojom_traits.h b/ui/gfx/mojom/ca_layer_params_mojom_traits.h
index 4cac766eae3161baedac4202f694129cd90c80de..0821495ad22944d8856bb750cac8912a2f8328c3 100644
--- a/ui/gfx/mojom/ca_layer_params_mojom_traits.h
+++ b/ui/gfx/mojom/ca_layer_params_mojom_traits.h
@@ -20,6 +20,10 @@ struct StructTraits<gfx::mojom::CALayerParamsDataView, gfx::CALayerParams> {
     return ca_layer_params.pixel_size;
   }
 
+  static gfx::Rect damage(const gfx::CALayerParams& ca_layer_params) {
+    return ca_layer_params.damage;
+  }
+
   static float scale_factor(const gfx::CALayerParams& ca_layer_params) {
     return ca_layer_params.scale_factor;
   }