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

chrome/browser/tab_contents/thumbnail_generator.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_BROWSER_TAB_CONTENTS_THUMBNAIL_GENERATOR_H_
 #define CHROME_BROWSER_TAB_CONTENTS_THUMBNAIL_GENERATOR_H_
 
 #include <map>
 #include <utility>
 #include <vector>
@@ skipping 62 matching lines @@
 #endif
 
  private:
   // RenderWidgetHostPaintingObserver implementation.
   virtual void WidgetWillDestroyBackingStore(RenderWidgetHost* widget,
                                              BackingStore* backing_store);
   virtual void WidgetDidUpdateBackingStore(RenderWidgetHost* widget);
 
   virtual void WidgetDidReceivePaintAtSizeAck(
       RenderWidgetHost* widget,
-      const TransportDIB::Handle& dib_handle,
+      int tag,
       const gfx::Size& size);
 
   // NotificationObserver interface.
   virtual void Observe(NotificationType type,
                        const NotificationSource& source,
                        const NotificationDetails& details);
 
   // Indicates that the given widget has changed is visibility.
   void WidgetShown(RenderWidgetHost* widget);
   void WidgetHidden(RenderWidgetHost* widget);
@@ skipping 17 matching lines @@
   base::OneShotTimer<ThumbnailGenerator> timer_;
 
   // A list of all RWHs that have been shown and need to have their thumbnail
   // expired at some time in the future with the "slop" time has elapsed. This
   // list will normally have 0 or 1 items in it.
   std::vector<RenderWidgetHost*> shown_hosts_;
 
   // See the setter above.
   bool no_timeout_;
 
-  // Map of callback objects by TransportDIB::Handle.
+  // Map of callback objects by sequence number.
   struct AsyncRequestInfo;
-  typedef std::map<TransportDIB::Handle,
+  typedef std::map<int,
                    linked_ptr<AsyncRequestInfo> > ThumbnailCallbackMap;
   ThumbnailCallbackMap callback_map_;
 
   DISALLOW_COPY_AND_ASSIGN(ThumbnailGenerator);
 };
 
 #endif  // CHROME_BROWSER_TAB_CONTENTS_THUMBNAIL_GENERATOR_H_