Fixed bug that caused canvas updates to trigger two compositor paints.

content/renderer/render_widget.h

 // Copyright (c) 2011 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_WIDGET_H_
 #define CONTENT_RENDERER_RENDER_WIDGET_H_
 #pragma once
 
 #include <vector>
 
@@ skipping 84 matching lines @@
 
   // IPC::Message::Sender
   virtual bool Send(IPC::Message* msg);
 
   // WebKit::WebWidgetClient
   virtual void didInvalidateRect(const WebKit::WebRect&);
   virtual void didScrollRect(int dx, int dy, const WebKit::WebRect& clipRect);
   virtual void didActivateAcceleratedCompositing(bool active);
   virtual void scheduleComposite();
   virtual void scheduleAnimation();
+  virtual void popPendingUpdate();
   virtual void didFocus();
   virtual void didBlur();
   virtual void didChangeCursor(const WebKit::WebCursorInfo&);
   virtual void closeWidgetSoon();
   virtual void show(WebKit::WebNavigationPolicy);
   virtual void runModal() {}
   virtual WebKit::WebRect windowRect();
   virtual void setToolTipText(const WebKit::WebString& text,
                               WebKit::WebTextDirection hint);
   virtual void setWindowRect(const WebKit::WebRect&);
@@ skipping 212 matching lines @@
   // messages.
   WebCursor current_cursor_;
 
   // The size of the RenderWidget.
   gfx::Size size_;
 
   // The TransportDIB that is being used to transfer an image to the browser.
   TransportDIB* current_paint_buf_;
 
   PaintAggregator paint_aggregator_;
+  PaintAggregator::PendingUpdate paint_aggregator_update_;
 
   // The area that must be reserved for drawing the resize corner.
   gfx::Rect resizer_rect_;
 
   // Flags for the next ViewHostMsg_UpdateRect message.
   int next_paint_flags_;
 
   // Filtered time per frame based on UpdateRect messages.
   float filtered_time_per_frame_;
 
@@ skipping 85 matching lines @@
   bool animation_task_posted_;
   bool invalidation_task_posted_;
 
   bool has_disable_gpu_vsync_switch_;
   base::TimeTicks last_do_deferred_update_time_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidget);
 };
 
 #endif  // CONTENT_RENDERER_RENDER_WIDGET_H_