[cc] Pass on BeginFrameAcks from CompositorEBFS through RWHVAura, DFH.

content/browser/renderer_host/render_widget_host_view_aura.h

Index: content/browser/renderer_host/render_widget_host_view_aura.h
diff --git a/content/browser/renderer_host/render_widget_host_view_aura.h b/content/browser/renderer_host/render_widget_host_view_aura.h
index 818fcdc232908412d4ff4eb76f9097bf88b60cd8..77f9f086fbb90b368deb033bbdd5080447a46314 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.h
+++ b/content/browser/renderer_host/render_widget_host_view_aura.h
@@ -21,6 +21,7 @@
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "build/build_config.h"
+#include "cc/output/begin_frame_args.h"
 #include "cc/scheduler/begin_frame_source.h"
 #include "content/browser/accessibility/browser_accessibility_manager.h"
 #include "content/browser/compositor/image_transport_factory.h"
@@ -166,6 +167,7 @@ class CONTENT_EXPORT RenderWidgetHostViewAura
   void UnlockMouse() override;
   void OnSwapCompositorFrame(uint32_t compositor_frame_sink_id,
                              cc::CompositorFrame frame) override;
+  void OnBeginFrameDidNotSwap(const cc::BeginFrameAck& ack) override;
   void ClearCompositorFrame() override;
   void DidStopFlinging() override;
   void OnDidNavigateMainFrameToNewPage() override;
@@ -362,6 +364,8 @@ class CONTENT_EXPORT RenderWidgetHostViewAura
                            OverscrollResetsOnBlur);
   FRIEND_TEST_ALL_PREFIXES(RenderWidgetHostViewAuraTest,
                            FinishCompositionByMouse);
+  FRIEND_TEST_ALL_PREFIXES(RenderWidgetHostViewAuraTest,
+                           ForwardsBeginFrameAcks);
   FRIEND_TEST_ALL_PREFIXES(WebContentsViewAuraTest,
                            WebContentsViewReparent);
 
@@ -507,6 +511,7 @@ class CONTENT_EXPORT RenderWidgetHostViewAura
   // The begin frame source being observed.  Null if none.
   cc::BeginFrameSource* begin_frame_source_;
   cc::BeginFrameArgs last_begin_frame_args_;
+  uint64_t latest_confirmed_begin_frame_sequence_number_;
 
   // Whether a request for begin frames has been issued.
   bool needs_begin_frames_;