Transfer theme & page background colors between changes of RWHV.

chrome/browser/ui/views/frame/contents_web_view.cc

 // 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 "chrome/browser/ui/views/frame/contents_web_view.h"
 
 #include "chrome/browser/themes/theme_properties.h"
 #include "chrome/browser/ui/views/status_bubble_views.h"
+#include "content/public/browser/render_frame_host.h"
 #include "content/public/browser/render_widget_host_view.h"
 #include "content/public/browser/web_contents.h"
 #include "ui/base/theme_provider.h"
 #include "ui/compositor/layer_tree_owner.h"
 #include "ui/views/background.h"
 
 #if defined(USE_AURA)
 #include "ui/aura/window.h"
 #include "ui/wm/core/window_util.h"
 #endif
@@ skipping 103 matching lines @@
   cloned_layer_tree_.reset();
   SetPaintToLayer(false);
   set_layer_owner_delegate(nullptr);
 }
 
 void ContentsWebView::RenderViewReady() {
   // Apply the theme color to be the default background on startup.
   OnThemeChanged();
   WebView::RenderViewReady();
 }
+
+void ContentsWebView::RenderFrameHostChanged(
+    content::RenderFrameHost* old_host, content::RenderFrameHost* new_host) {
+  // Pass the background color of the old host to the new one. This passes
+  // on the page background color of the old host (or the theme color if the
+  // page background color is not set). This avoids flashes of white when
+  // starting up new_host.
+  if (old_host && new_host)

[sky, 2016/05/04 20:39:09]

If this is the right change, can't we do it entirely in content?

[chrishtr, 2016/05/04 21:10:18]

I'm not sure what you mean. What do you mean by "in content"?

[sky, 2016/05/04 21:48:06]

Content knows when the renderframehost is changing (content is calling this
code). I'm suggesting this code be moved there.

[chrishtr, 2016/05/04 23:07:16]

Done (hope I understood your suggestion).

Should the same be done for RenderViewReady()?

+    new_host->GetView()->SetBackgroundColor(
+        old_host->GetView()->background_color());
+  WebView::RenderFrameHostChanged(old_host, new_host);
+}