[blink] Support (semi-)transparent background colors in WebView/Frame.

third_party/WebKit/Source/web/WebViewImpl.h

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 489 matching lines @@
   double lastFrameTimeMonotonic() const { return m_lastFrameTimeMonotonic; }
 
   ChromeClientImpl& chromeClient() const { return *m_chromeClientImpl.get(); }
 
   // Returns the currently active WebInputMethodController which is the one
   // corresponding to the focused frame. It will return nullptr if there is no
   // focused frame, or if the there is one but it belongs to a different local
   // root.
   WebInputMethodControllerImpl* getActiveWebInputMethodController() const;
 
+  void updateLayerTreeBackgroundColor();
+
  private:
   InspectorOverlay* inspectorOverlay();
 
   void setPageScaleFactorAndLocation(float, const FloatPoint&);
   void propagateZoomFactorToLocalFrameRoots(Frame*, float);
 
   void scrollAndRescaleViewports(float scaleFactor,
                                  const IntPoint& mainFrameOrigin,
                                  const FloatPoint& visualViewportOrigin);
 
@@ skipping 29 matching lines @@
   HitTestResult hitTestResultForViewportPos(const IntPoint&);
 
   void configureAutoResizeMode();
 
   void initializeLayerTreeView();
 
   void setIsAcceleratedCompositingActive(bool);
   void doComposite();
   void reallocateRenderer();
   void updateLayerTreeViewport();
-  void updateLayerTreeBackgroundColor();
   void updateDeviceEmulationTransform();
   void updateLayerTreeDeviceScaleFactor();
 
   // Helper function: Widens the width of |source| by the specified margins
   // while keeping it smaller than page width.
   WebRect widenRectWithinPageBounds(const WebRect& source,
                                     int targetMargin,
                                     int minimumMargin);
 
   // PageWidgetEventHandler functions
@@ skipping 172 matching lines @@
   Persistent<ResizeViewportAnchor> m_resizeViewportAnchor;
 };
 
 // We have no ways to check if the specified WebView is an instance of
 // WebViewImpl because WebViewImpl is the only implementation of WebView.
 DEFINE_TYPE_CASTS(WebViewImpl, WebView, webView, true, true);
 
 }  // namespace blink
 
 #endif