fix: ensure child window transparency (#28107)

* fix: ensure child window transparency works

Windows opened via window.open and intecepted via setWindowOpenHandler
or the `new-window` event should (a) have the correct background color
and (b) that background color should be transparent if specified.

The changes in api_web_contents fix (a) and the changes in
web_contents_preferences fix (b).

Notes: Child windows with specified background colors or transpency now
work as intended

* fix: set background_color in blink prefs apply logic

* fix: apply changes for 12

* fix: background_color patch simplification

* update patches

Co-authored-by: Samuel Attard <sattard@slack-corp.com>
Co-authored-by: Electron Bot <electron@github.com>

lib/browser/api/web-contents.ts

@@ -626,6 +626,7 @@ WebContents.prototype._init = function () {
           // it's technically a BrowserWindowConstructorOptions option because
           // we need to access it in the renderer at init time.
           backgroundColor: windowOpenOverriddenOptions.backgroundColor,
+          transparent: windowOpenOverriddenOptions.transparent,
           ...windowOpenOverriddenOptions.webPreferences
         } : undefined;
         this._setNextChildWebPreferences(

patches/chromium/.patches

@@ -110,3 +110,4 @@ don_t_use_potentially_null_getwebframe_-_view_when_get_blink.patch
 cherry-pick-5902d1aa722a.patch
 cherry-pick-5c7ad5393f74.patch
 word_break_between_space_and_alphanumeric.patch
+moves_background_color_setter_of_webview_to_blinks_webprefs_logic.patch

patches/chromium/moves_background_color_setter_of_webview_to_blinks_webprefs_logic.patch

@@ -0,0 +1,40 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Samuel Attard <sattard@slack-corp.com>
+Date: Mon, 8 Mar 2021 16:27:39 -0800
+Subject: moves background_color setter of WebView to blinks webprefs logic
+
+background_color can be updated at runtime, as such we need to apply the
+new background color to the WebView in the ApplyPreferences method.
+There is no current way to attach an observer to these prefs so patching
+is our only option.
+
+Ideally we could add an embedder observer pattern here but that can be
+done in future work.
+
+diff --git a/third_party/blink/renderer/core/exported/web_view_impl.cc b/third_party/blink/renderer/core/exported/web_view_impl.cc
+index 755d037d6f5046d4641b6532918125d1ca84cdd8..adeb4845fe5f8516cb4d2ed36cb59bb26d714b9b 100644
+--- a/third_party/blink/renderer/core/exported/web_view_impl.cc
++++ b/third_party/blink/renderer/core/exported/web_view_impl.cc
+@@ -154,6 +154,7 @@
+ #include "third_party/blink/renderer/core/timing/dom_window_performance.h"
+ #include "third_party/blink/renderer/core/timing/window_performance.h"
+ #include "third_party/blink/renderer/platform/fonts/font_cache.h"
++#include "third_party/blink/renderer/platform/graphics/color.h"
+ #include "third_party/blink/renderer/platform/graphics/image.h"
+ #include "third_party/blink/renderer/platform/graphics/paint/cull_rect.h"
+ #include "third_party/blink/renderer/platform/graphics/paint/paint_record_builder.h"
+@@ -1752,6 +1753,14 @@ void WebView::ApplyWebPreferences(const web_pref::WebPreferences& prefs,
+ 
+   RuntimeEnabledFeatures::SetTranslateServiceEnabled(
+       prefs.translate_service_available);
++
++  SkColor color = SK_ColorTRANSPARENT;
++  if (!prefs.guest_instance_id) {  // not inside electron <webview /> tag, which is always transparent.
++    Color blink_color;
++    if (blink_color.SetFromString(WebString::FromASCII(prefs.background_color)))
++      color = static_cast<SkColor>(blink_color);
++  }
++  web_view->SetBaseBackgroundColor(color);
+ }
+ 
+ void WebViewImpl::ThemeChanged() {

shell/browser/api/electron_api_web_contents.cc

@@ -1055,6 +1055,16 @@ void WebContents::AddNewContents(
   v8::HandleScope handle_scope(isolate);
   auto api_web_contents =
       CreateAndTake(isolate, std::move(new_contents), Type::kBrowserWindow);
+
+  // We call RenderFrameCreated here as at this point the empty "about:blank"
+  // render frame has already been created.  If the window never navigates again
+  // RenderFrameCreated won't be called and certain prefs like
+  // "kBackgroundColor" will not be applied.
+  auto* frame = api_web_contents->MainFrame();
+  if (frame) {
+    api_web_contents->HandleNewRenderFrame(frame);
+  }
+
   if (Emit("-add-new-contents", api_web_contents, disposition, user_gesture,
            initial_rect.x(), initial_rect.y(), initial_rect.width(),
            initial_rect.height(), tracker->url, tracker->frame_name,
@@ -1353,30 +1363,27 @@ void WebContents::BeforeUnloadFired(bool proceed,
   // there are two virtual functions named BeforeUnloadFired.
 }
 
-void WebContents::RenderViewCreated(content::RenderViewHost* render_view_host) {
-  if (!background_throttling_)
-    render_view_host->SetSchedulerThrottling(false);
-
-  // Set the background color of RenderWidgetHostView.
-  auto* const view = web_contents()->GetRenderWidgetHostView();
-  auto* web_preferences = WebContentsPreferences::From(web_contents());
-  if (view && web_preferences) {
-    std::string color_name;
-    if (web_preferences->GetPreference(options::kBackgroundColor,
-                                       &color_name)) {
-      view->SetBackgroundColor(ParseHexColor(color_name));
-    } else {
-      view->SetBackgroundColor(SK_ColorTRANSPARENT);
-    }
-  }
-}
-
-void WebContents::RenderFrameCreated(
+void WebContents::HandleNewRenderFrame(
     content::RenderFrameHost* render_frame_host) {
   auto* rwhv = render_frame_host->GetView();
   if (!rwhv)
     return;
 
+  // Set the background color of RenderWidgetHostView.
+  auto* web_preferences = WebContentsPreferences::From(web_contents());
+  if (web_preferences) {
+    std::string color_name;
+    if (web_preferences->GetPreference(options::kBackgroundColor,
+                                       &color_name)) {
+      rwhv->SetBackgroundColor(ParseHexColor(color_name));
+    } else {
+      rwhv->SetBackgroundColor(SK_ColorTRANSPARENT);
+    }
+  }
+
+  if (!background_throttling_)
+    render_frame_host->GetRenderViewHost()->SetSchedulerThrottling(false);
+
   auto* rwh_impl =
       static_cast<content::RenderWidgetHostImpl*>(rwhv->GetRenderWidgetHost());
   if (rwh_impl)
@@ -1385,6 +1392,11 @@ void WebContents::RenderFrameCreated(
   WebFrameMain::RenderFrameCreated(render_frame_host);
 }
 
+void WebContents::RenderFrameCreated(
+    content::RenderFrameHost* render_frame_host) {
+  HandleNewRenderFrame(render_frame_host);
+}
+
 void WebContents::RenderViewDeleted(content::RenderViewHost* render_view_host) {
   // This event is necessary for tracking any states with respect to
   // intermediate render view hosts aka speculative render view hosts. Currently

shell/browser/api/electron_api_web_contents.h

@@ -211,6 +211,7 @@ class WebContents : public gin::Wrappable<WebContents>,
   void IncrementCapturerCount(gin::Arguments* args);
   void DecrementCapturerCount(gin::Arguments* args);
   bool IsBeingCaptured();
+  void HandleNewRenderFrame(content::RenderFrameHost* render_frame_host);
 
 #if BUILDFLAG(ENABLE_PRINTING)
   void OnGetDefaultPrinter(base::Value print_settings,
@@ -550,7 +551,6 @@ class WebContents : public gin::Wrappable<WebContents>,
   // content::WebContentsObserver:
   void BeforeUnloadFired(bool proceed,
                          const base::TimeTicks& proceed_time) override;
-  void RenderViewCreated(content::RenderViewHost* render_view_host) override;
   void RenderFrameCreated(content::RenderFrameHost* render_frame_host) override;
   void RenderViewDeleted(content::RenderViewHost*) override;
   void RenderProcessGone(base::TerminationStatus status) override;

shell/renderer/renderer_client_base.cc

@@ -265,22 +265,6 @@ void RendererClientBase::RenderFrameCreated(
   // service_impl_.reset(new ElectronApiServiceImpl(render_frame, this));
   new ElectronApiServiceImpl(render_frame, this);
 
-  content::RenderView* render_view = render_frame->GetRenderView();
-  if (render_frame->IsMainFrame() && render_view) {
-    blink::WebView* webview = render_view->GetWebView();
-    if (webview) {
-      auto prefs = render_frame->GetBlinkPreferences();
-      if (prefs.guest_instance_id) {  // webview.
-        webview->SetBaseBackgroundColor(SK_ColorTRANSPARENT);
-      } else {  // normal window.
-        std::string name = prefs.background_color;
-        SkColor color =
-            name.empty() ? SK_ColorTRANSPARENT : ParseHexColor(name);
-        webview->SetBaseBackgroundColor(color);
-      }
-    }
-  }
-
 #if BUILDFLAG(ENABLE_ELECTRON_EXTENSIONS)
   auto* dispatcher = extensions_renderer_client_->GetDispatcher();
   // ExtensionFrameHelper destroys itself when the RenderFrame is destroyed.