cc: Introduce BeginFrame sequence numbers and acknowledgements.

cc/trees/proxy_impl.cc

 // Copyright 2015 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 "cc/trees/proxy_impl.h"
 
 #include <algorithm>
 #include <string>
 
 #include "base/auto_reset.h"
@@ skipping 563 matching lines @@
   // request completes, and we signal completion here. If CanDraw() is false, we
   // will indicate success=false to the caller, but we must still signal
   // completion to avoid deadlock.
 
   // We guard PrepareToDraw() with CanDraw() because it always returns a valid
   // frame, so can only be used when such a frame is possible. Since
   // DrawLayers() depends on the result of PrepareToDraw(), it is guarded on
   // CanDraw() as well.
 
   LayerTreeHostImpl::FrameData frame;
+  frame.begin_frame_source_id = scheduler_->CurrentBeginFrameSourceId();
+  frame.begin_frame_number = scheduler_->CurrentBeginFrameNumber();
+  frame.latest_confirmed_frame =
+      scheduler_->LatestConfirmedFrameForActiveTree();
   bool draw_frame = false;
 
   DrawResult result;
   if (layer_tree_host_impl_->CanDraw()) {
     result = layer_tree_host_impl_->PrepareToDraw(&frame);
     draw_frame = forced_draw || result == DRAW_SUCCESS;
   } else {
     result = DRAW_ABORTED_CANT_DRAW;
   }
 
@@ skipping 34 matching lines @@
 ProxyImpl::BlockedMainCommitOnly& ProxyImpl::blocked_main_commit() {
   DCHECK(IsMainThreadBlocked() && commit_completion_event_);
   return main_thread_blocked_commit_vars_unsafe_;
 }
 
 base::SingleThreadTaskRunner* ProxyImpl::MainThreadTaskRunner() {
   return task_runner_provider_->MainThreadTaskRunner();
 }
 
 }  // namespace cc