Deliver IPC messages together with SwapCompositorFrame

content/renderer/render_widget.h

Index: content/renderer/render_widget.h
diff --git a/content/renderer/render_widget.h b/content/renderer/render_widget.h
index a4f988db475f838a0c5e5fb4706be394af886bdb..066461d005c65b874e39661d63ca316e6600cf4a 100644
--- a/content/renderer/render_widget.h
+++ b/content/renderer/render_widget.h
@@ -9,6 +9,7 @@
 #include <map>
 
 #include "base/basictypes.h"
+#include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
@@ -66,6 +67,7 @@ class Range;
 
 namespace content {
 class ExternalPopupMenu;
+class FrameSwapMessageQueue;
 class PepperPluginInstanceImpl;
 class RenderFrameImpl;
 class RenderWidgetCompositor;
@@ -176,6 +178,13 @@ class CONTENT_EXPORT RenderWidget
   // Notifies about a compositor frame commit operation having finished.
   virtual void DidCommitCompositorFrame();
 
+  // If the RenderWidget doesn't need a commit this is equivalent to Send,
+  // otherwise this will make sure |msg| is delivered with a frame swap
+  // coresponding to the commit that is about to occur.
+  //
+  // |msg| message to send, ownership of |msg| is transferred.
+  void QueueMessage(IPC::Message* msg);
+
   // Handle common setup/teardown for handling IME events.
   void StartHandlingImeEvent();
   void FinishHandlingImeEvent();
@@ -687,6 +696,7 @@ class CONTENT_EXPORT RenderWidget
   gfx::Point popup_screen_origin_for_emulation_;
   float popup_origin_scale_for_emulation_;
 
+  scoped_refptr<FrameSwapMessageQueue> frame_swap_message_queue_;
   scoped_ptr<ResizingModeSelector> resizing_mode_selector_;
 
   // A list of swapped out RenderFrames that need to be notified