Revert of Remove CompositorObserver::OnCompositingEnded()

ui/compositor/compositor.cc

 // Copyright (c) 2012 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 "ui/compositor/compositor.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <deque>
@@ skipping 484 matching lines @@
 }
 
 void Compositor::DidCommit() {
   DCHECK(!IsLocked());
   for (auto& observer : observer_list_)
     observer.OnCompositingDidCommit(this);
 }
 
 void Compositor::DidReceiveCompositorFrameAck() {
   ++activated_frame_count_;
+  for (auto& observer : observer_list_)
+    observer.OnCompositingEnded(this);
 }
 
 void Compositor::DidSubmitCompositorFrame() {
   base::TimeTicks start_time = base::TimeTicks::Now();
   for (auto& observer : observer_list_)
     observer.OnCompositingStarted(this, start_time);
 }
 
 void Compositor::SetOutputIsSecure(bool output_is_secure) {
   if (context_factory_private_)
@@ skipping 55 matching lines @@
 void Compositor::TimeoutLocks() {
   // Make a copy, we're going to cause |active_locks_| to become
   // empty.
   std::vector<CompositorLock*> locks = active_locks_;
   for (auto* lock : locks)
     lock->TimeoutLock();
   DCHECK(active_locks_.empty());
 }
 
 }  // namespace ui