Let PaintAtAck send an int tag instead of the TransportDIB handle.

chrome/renderer/render_widget.h

 // Copyright (c) 2009 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_WIDGET_H_
 #define CHROME_RENDERER_RENDER_WIDGET_H_
 
 #include <vector>
 
 #include "app/surface/transport_dib.h"
@@ skipping 148 matching lines @@
   void OnMouseCaptureLost();
   virtual void OnSetFocus(bool enable);
   void OnSetInputMethodActive(bool is_active);
   void OnImeSetComposition(
       const string16& text,
       const std::vector<WebKit::WebCompositionUnderline>& underlines,
       int selection_start,
       int selection_end);
   void OnImeConfirmComposition();
   void OnMsgPaintAtSize(const TransportDIB::Handle& dib_id,
+                        int tag,
                         const gfx::Size& page_size,
                         const gfx::Size& desired_size);
   void OnMsgRepaint(const gfx::Size& size_to_paint);
   void OnSetTextDirection(WebKit::WebTextDirection direction);
 
   // Override point to notify derived classes that a paint has happened.
   // DidInitiatePaint happens when we've generated a new bitmap and sent it to
   // the browser. DidFlushPaint happens once we've received the ACK that the
   // screen has actually been updated.
   virtual void DidInitiatePaint() {}
@@ skipping 138 matching lines @@
   // Indicates if the next sequence of Char events should be suppressed or not.
   bool suppress_next_char_events_;
 
   // Set to true if painting to the window is handled by the GPU process.
   bool is_gpu_rendering_active_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidget);
 };
 
 #endif  // CHROME_RENDERER_RENDER_WIDGET_H_