cc: Introduce BeginFrame sequence numbers and acknowledgements.

content/browser/renderer_host/browser_compositor_view_mac.h

Index: content/browser/renderer_host/browser_compositor_view_mac.h
diff --git a/content/browser/renderer_host/browser_compositor_view_mac.h b/content/browser/renderer_host/browser_compositor_view_mac.h
index 865b29ffa501c5586283eb5ed8f8de195a09aa77..ce1b7948cf078be835187e8c37908da776239861 100644
--- a/content/browser/renderer_host/browser_compositor_view_mac.h
+++ b/content/browser/renderer_host/browser_compositor_view_mac.h
@@ -8,6 +8,7 @@
 #include <memory>
 
 #include "base/macros.h"
+#include "cc/output/begin_frame_args.h"
 #include "cc/scheduler/begin_frame_source.h"
 #include "content/browser/renderer_host/delegated_frame_host.h"
 #include "ui/compositor/compositor.h"
@@ -62,6 +63,7 @@ class BrowserCompositorMac : public cc::BeginFrameObserver,
 
   void SwapCompositorFrame(uint32_t compositor_frame_sink_id,
                            cc::CompositorFrame frame);
+  void OnBeginFrameDidNotDraw(const cc::BeginFrameAck& ack);
   void SetHasTransparentBackground(bool transparent);
   void SetDisplayColorSpace(const gfx::ColorSpace& color_space);
   void UpdateVSyncParameters(const base::TimeTicks& timebase,
@@ -179,6 +181,7 @@ class BrowserCompositorMac : public cc::BeginFrameObserver,
   // The begin frame source being observed.  Null if none.
   cc::BeginFrameSource* begin_frame_source_ = nullptr;
   cc::BeginFrameArgs last_begin_frame_args_;
+  uint64_t latest_confirmed_frame_ = cc::BeginFrameArgs::kInvalidFrameNumber;
   bool needs_begin_frames_ = false;
 
   base::WeakPtrFactory<BrowserCompositorMac> weak_factory_;