Delete background tab IOSurfaces on Mac.

content/browser/gpu/gpu_process_host.h

Index: content/browser/gpu/gpu_process_host.h
diff --git a/content/browser/gpu/gpu_process_host.h b/content/browser/gpu/gpu_process_host.h
index f101c6c3d4ff940708b24da479df589db44e1705..d745c045bc13233f0e3a6c6254d7c2a69ab08835 100644
--- a/content/browser/gpu/gpu_process_host.h
+++ b/content/browser/gpu/gpu_process_host.h
@@ -29,6 +29,7 @@ struct GpuHostMsg_AcceleratedSurfacePostSubBuffer_Params;
 struct GpuHostMsg_AcceleratedSurfaceRelease_Params;
 
 class BrowserChildProcessHostImpl;
+class RenderWidgetHelper;
 
 class GpuProcessHost : public content::BrowserChildProcessHostDelegate,
                        public IPC::Message::Sender,
@@ -95,6 +96,13 @@ class GpuProcessHost : public content::BrowserChildProcessHostDelegate,
 
   void ForceShutdown();
 
+  // The GpuMessageFilter hands over the RenderWidgetHelper so we can call
+  // DidReceiveUpdateMsg when SwapBuffers arrive.
+  void RegisterRenderWidgetHelper(
+      int render_process_id,
+      const scoped_refptr<RenderWidgetHelper>& render_widget_helper);
+  void UnregisterRenderWidgetHelper(int render_process_id);
+
  private:
   static bool HostIsValid(GpuProcessHost* host);
 
@@ -117,6 +125,10 @@ class GpuProcessHost : public content::BrowserChildProcessHostDelegate,
   void OnCommandBufferCreated(const int32 route_id);
   void OnDestroyCommandBuffer(int32 surface_id);
 
+#if defined(OS_MACOSX)
+  void OnAcceleratedSurfaceBuffersSwapped(
+      const GpuHostMsg_AcceleratedSurfaceBuffersSwapped_Params& params);
+#endif
 #if defined(OS_WIN) && !defined(USE_AURA)
   void OnAcceleratedSurfaceBuffersSwapped(
       const GpuHostMsg_AcceleratedSurfaceBuffersSwapped_Params& params);
@@ -188,6 +200,8 @@ class GpuProcessHost : public content::BrowserChildProcessHostDelegate,
 
   scoped_ptr<BrowserChildProcessHostImpl> process_;
 
+  std::map<int, scoped_refptr<RenderWidgetHelper> > render_widget_helpers_;
+
   DISALLOW_COPY_AND_ASSIGN(GpuProcessHost);
 };