Delay UpdateRect until the SwapBuffers callback when accelerated compositing is on.

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 b091c96dc3416fa3d9adf8232a6f316643552aff..70259c1fb6fdb3be3c04505d08c72ab824e647b4 100644
--- a/content/renderer/render_widget.h
+++ b/content/renderer/render_widget.h
@@ -6,6 +6,7 @@
 #define CONTENT_RENDERER_RENDER_WIDGET_H_
 #pragma once
 
+#include <deque>
 #include <vector>
 
 #include "base/basictypes.h"
@@ -29,6 +30,9 @@
 #include "ui/gfx/surface/transport_dib.h"
 #include "webkit/glue/webcursor.h"
 
+struct ViewHostMsg_UpdateRect_Params;
+class ViewHostMsg_UpdateRect;
+
 namespace IPC {
 class SyncMessage;
 }
@@ -274,11 +278,6 @@ class CONTENT_EXPORT RenderWidget
   void WillToggleFullscreen();
   void DidToggleFullscreen();
 
-  // True if an UpdateRect_ACK message is pending.
-  bool update_reply_pending() const {
-    return update_reply_pending_;
-  }
-
   bool next_paint_is_resize_ack() const;
   bool next_paint_is_restore_ack() const;
   void set_next_paint_is_resize_ack();
@@ -471,6 +470,17 @@ class CONTENT_EXPORT RenderWidget
   bool has_disable_gpu_vsync_switch_;
   base::TimeTicks last_do_deferred_update_time_;
 
+  // UpdateRect parameters for the current compositing pass. This is used to
+  // pass state between DoDeferredUpdate and OnSwapBuffersPosted.
+  scoped_ptr<ViewHostMsg_UpdateRect_Params> pending_update_params_;
+
+  // Queue of UpdateRect messages corresponding to a SwapBuffers. We want to
+  // delay sending of UpdateRect until the corresponding SwapBuffers has been
+  // executed. Since we can have several in flight, we need to keep them in a
+  // queue. Note: some SwapBuffers may not correspond to an update, in which
+  // case NULL is added to the queue.
+  std::deque<ViewHostMsg_UpdateRect*> updates_pending_swap_;
+
   DISALLOW_COPY_AND_ASSIGN(RenderWidget);
 };