Mac: Don't hang gpu process on popup close under certain conditions

chrome/gpu/gpu_thread.h

Index: chrome/gpu/gpu_thread.h
diff --git a/chrome/gpu/gpu_thread.h b/chrome/gpu/gpu_thread.h
index 9aba2fdfbf401b8d20fe3efbd2c49ae381e59ffa..a4a1948a01bfdd66da95759b8c25a131857cc402 100644
--- a/chrome/gpu/gpu_thread.h
+++ b/chrome/gpu/gpu_thread.h
@@ -43,6 +43,7 @@ class GpuThread : public ChildThread {
 #if defined(OS_MACOSX)
   void OnAcceleratedSurfaceBuffersSwappedACK(
       int renderer_id, int32 route_id, uint64 swap_buffers_count);
+  void OnDidDestroySurface(int renderer_id, int32 renderer_route_id);
 #endif
   void OnCrash();
   void OnHang();