cc: Introduce BeginFrame sequence numbers and acknowledgements.

services/ui/ws/frame_generator.cc

 // Copyright 2016 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.
 
 #include "services/ui/ws/frame_generator.h"
 
 #include <utility>
 
 #include "base/containers/adapters.h"
 #include "cc/output/compositor_frame.h"
@@ skipping 71 matching lines @@
   // SurfaceId to all embedded surfaces. For example, this would happen when the
   // display resolution or device scale factor changes.
   if (window == root_window_)
     AddNewParentReferences(old_surface_id, surface_id);
 
   PerformAddSurfaceReferences();
 }
 
 void FrameGenerator::DidReceiveCompositorFrameAck() {}
 
-void FrameGenerator::OnBeginFrame(const cc::BeginFrameArgs& begin_frame_arags) {
+void FrameGenerator::OnBeginFrame(const cc::BeginFrameArgs& begin_frame_args) {
   if (!root_window_->visible())
     return;
 
   // TODO(fsamuel): We should add a trace for generating a top level frame.
   cc::CompositorFrame frame(GenerateCompositorFrame(root_window_->bounds()));
+  frame.metadata.begin_frame_number = begin_frame_args.sequence_number;
+  frame.metadata.oldest_incorporated_frame = begin_frame_args.sequence_number;
 
   if (compositor_frame_sink_) {
     gfx::Size frame_size = last_submitted_frame_size_;
     if (!frame.render_pass_list.empty())
       frame_size = frame.render_pass_list[0]->output_rect.size();
     if (!local_frame_id_.is_valid() || frame_size != last_submitted_frame_size_)
       local_frame_id_ = id_allocator_.GenerateId();
     compositor_frame_sink_->SubmitCompositorFrame(local_frame_id_,
                                                   std::move(frame));
     last_submitted_frame_size_ = frame_size;
@@ skipping 235 matching lines @@
   cc::SurfaceId underlay_surface_id =
       window->compositor_frame_sink_manager()->GetLatestSurfaceId(
           mojom::CompositorFrameSinkType::UNDERLAY);
   if (underlay_surface_id.is_valid())
     RemoveFrameSinkReference(underlay_surface_id.frame_sink_id());
 }
 
 }  // namespace ws
 
 }  // namespace ui