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

chrome/browser/renderer_host/render_widget_host.h

Index: chrome/browser/renderer_host/render_widget_host.h
diff --git a/chrome/browser/renderer_host/render_widget_host.h b/chrome/browser/renderer_host/render_widget_host.h
index c7e3cd663486a55c08fa6dd51e713d8e9a2d156f..27e50b49882acc21b59b526f802209062ca68656 100644
--- a/chrome/browser/renderer_host/render_widget_host.h
+++ b/chrome/browser/renderer_host/render_widget_host.h
@@ -222,6 +222,7 @@ class RenderWidgetHost : public IPC::Channel::Listener,
   // logic that is normally invoked, and doesn't put the results into
   // the backing store.
   void PaintAtSize(TransportDIB::Handle dib_handle,
+                   int tag,
                    const gfx::Size& page_size,
                    const gfx::Size& desired_size);
 
@@ -476,8 +477,7 @@ class RenderWidgetHost : public IPC::Channel::Listener,
   void OnMsgRenderViewGone();
   void OnMsgClose();
   void OnMsgRequestMove(const gfx::Rect& pos);
-  void OnMsgPaintAtSizeAck(const TransportDIB::Handle& dib_handle,
-                           const gfx::Size& size);
+  void OnMsgPaintAtSizeAck(int tag, const gfx::Size& size);
   void OnMsgUpdateRect(const ViewHostMsg_UpdateRect_Params& params);
   void OnMsgCreateVideo(const gfx::Size& size);
   void OnMsgUpdateVideo(TransportDIB::Id bitmap, const gfx::Rect& bitmap_rect);