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

content/browser/renderer_host/delegated_frame_host.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_BROWSER_RENDERER_HOST_DELEGATED_FRAME_HOST_H_
 #define CONTENT_BROWSER_RENDERER_HOST_DELEGATED_FRAME_HOST_H_
 
 #include <stdint.h>
 
 #include <vector>
 
 #include "base/gtest_prod_util.h"
+#include "cc/output/begin_frame_args.h"
 #include "cc/output/copy_output_result.h"
 #include "cc/scheduler/begin_frame_source.h"
 #include "cc/surfaces/compositor_frame_sink_support_client.h"
 #include "content/browser/compositor/image_transport_factory.h"
 #include "content/browser/compositor/owned_mailbox.h"
 #include "content/browser/renderer_host/delegated_frame_evictor.h"
 #include "content/browser/renderer_host/dip_util.h"
 #include "content/browser/renderer_host/render_widget_host_impl.h"
 #include "content/browser/renderer_host/render_widget_host_view_base.h"
 #include "content/public/browser/render_process_host.h"
@@ skipping 304 matching lines @@
   // Callback used to pass the output request to the layer or to a function
   // specified by a test.
   base::Callback<void(std::unique_ptr<cc::CopyOutputRequest>)>
       request_copy_of_output_callback_for_testing_;
 
   // YUV readback pipeline.
   std::unique_ptr<display_compositor::ReadbackYUVInterface>
       yuv_readback_pipeline_;
 
   std::unique_ptr<cc::ExternalBeginFrameSource> begin_frame_source_;
-
   bool needs_begin_frame_ = false;
+  uint32_t latest_confirmed_begin_frame_source_id_ = 0;
+  uint64_t latest_confirmed_begin_frame_sequence_number_ =
+      cc::BeginFrameArgs::kInvalidFrameNumber;
 
   bool has_frame_ = false;
 
   std::unique_ptr<DelegatedFrameEvictor> delegated_frame_evictor_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_DELEGATED_FRAME_HOST_H_