Allow to have a transparent UA dependent background.

content/renderer/render_view_impl.h

 // Copyright (c) 2012 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 CONTENT_RENDERER_RENDER_VIEW_IMPL_H_
 #define CONTENT_RENDERER_RENDER_VIEW_IMPL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 641 matching lines @@
       const std::vector<content::FileChooserFileInfo>& files);
   void OnMediaPlayerActionAt(const gfx::Point& location,
                              const blink::WebMediaPlayerAction& action);
   void OnPluginActionAt(const gfx::Point& location,
                         const blink::WebPluginAction& action);
   void OnMoveOrResizeStarted();
   void OnReleaseDisambiguationPopupBitmap(const cc::SharedBitmapId& id);
   void OnResetPageEncodingToDefault();
   void OnSetActive(bool active);
   void OnSetBackgroundOpaque(bool opaque);
+  void OnSetBackgroundColor(SkColor color);
   void OnExitFullscreen();
   void OnSetHistoryOffsetAndLength(int history_offset, int history_length);
   void OnSetInitialFocus(bool reverse);
   void OnSetPageEncoding(const std::string& encoding_name);
   void OnSetRendererPrefs(const RendererPreferences& renderer_prefs);
   void OnSetWebUIProperty(const std::string& name, const std::string& value);
   void OnSetZoomLevelForLoadingURL(const GURL& url, double zoom_level);
   void OnSetZoomLevelForView(bool uses_temporary_zoom_level, double level);
   void OnSuppressDialogsUntilSwapOut();
   void OnThemeChanged();
@@ skipping 344 matching lines @@
   // use the Observer interface to filter IPC messages and receive frame change
   // notifications.
   // ---------------------------------------------------------------------------
 
   DISALLOW_COPY_AND_ASSIGN(RenderViewImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_RENDER_VIEW_IMPL_H_