Mac ÜC: Enable GPU back-pressure from the browser to the renderer

content/browser/compositor/delegated_frame_host.h

Index: content/browser/compositor/delegated_frame_host.h
diff --git a/content/browser/compositor/delegated_frame_host.h b/content/browser/compositor/delegated_frame_host.h
index 0095599e23c2380ec8c0adbf67caa3bcb5300197..7e98fe83cb318239c7c37ef6bdf277ba45fb30f0 100644
--- a/content/browser/compositor/delegated_frame_host.h
+++ b/content/browser/compositor/delegated_frame_host.h
@@ -42,6 +42,8 @@ class CONTENT_EXPORT DelegatedFrameHostClient {
   virtual ui::Layer* GetLayer() = 0;
   virtual RenderWidgetHostImpl* GetHost() = 0;
   virtual void SchedulePaintInRect(const gfx::Rect& damage_rect_in_dip) = 0;
+  virtual void DelegatedCompositorDidSwapBuffers() = 0;
+  virtual void DelegatedCompositorAbortedSwapBuffers() = 0;
   virtual bool IsVisible() = 0;
   virtual scoped_ptr<ResizeLock> CreateResizeLock(
       bool defer_compositor_lock) = 0;