Skip screen update when the WebView isn't ready to paint.

chrome/renderer/render_view.h

 // Copyright (c) 2010 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 CHROME_RENDERER_RENDER_VIEW_H_
 #define CHROME_RENDERER_RENDER_VIEW_H_
 #pragma once
 
 #include <deque>
 #include <map>
@@ skipping 592 matching lines @@
 
  protected:
   // RenderWidget overrides:
   virtual void Close();
   virtual void OnResize(const gfx::Size& new_size,
                         const gfx::Rect& resizer_rect);
   virtual void DidInitiatePaint();
   virtual void DidFlushPaint();
   virtual void DidHandleKeyEvent();
   virtual void DidHandleMouseEvent(const WebKit::WebMouseEvent& event);
+  virtual bool IsReadyToPaint() const;
 
 #if OS_MACOSX
   virtual void OnSetFocus(bool enable);
   virtual void OnWasHidden();
   virtual void OnWasRestored(bool needs_repainting);
 #endif
 
  private:
   // For unit tests.
   friend class RenderViewTest;
@@ skipping 723 matching lines @@
   // ADDING NEW DATA? Please see if it fits appropriately in one of the above
   // sections rather than throwing it randomly at the end. If you're adding a
   // bunch of stuff, you should probably create a helper class and put your
   // data and methods on that to avoid bloating RenderView more.
   // ---------------------------------------------------------------------------
 
   DISALLOW_COPY_AND_ASSIGN(RenderView);
 };
 
 #endif  // CHROME_RENDERER_RENDER_VIEW_H_