Standardize usage of virtual/override/final in cc/

cc/trees/layer_tree_host_impl.cc

 // Copyright 2011 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/layer_tree_host_impl.h"
 
 #include <algorithm>
 #include <limits>
 
 #include "base/basictypes.h"
@@ skipping 158 matching lines @@
 
 class LayerTreeHostImplTimeSourceAdapter : public TimeSourceClient {
  public:
   static scoped_ptr<LayerTreeHostImplTimeSourceAdapter> Create(
       LayerTreeHostImpl* layer_tree_host_impl,
       scoped_refptr<DelayBasedTimeSource> time_source) {
     return make_scoped_ptr(
         new LayerTreeHostImplTimeSourceAdapter(layer_tree_host_impl,
                                                time_source));
   }
-  virtual ~LayerTreeHostImplTimeSourceAdapter() {
+  ~LayerTreeHostImplTimeSourceAdapter() override {
     time_source_->SetClient(NULL);
     time_source_->SetActive(false);
   }
 
-  virtual void OnTimerTick() override {
+  void OnTimerTick() override {
     // In single threaded mode we attempt to simulate changing the current
     // thread by maintaining a fake thread id. When we switch from one
     // thread to another, we construct DebugScopedSetXXXThread objects that
     // update the thread id. This lets DCHECKS that ensure we're on the
     // right thread to work correctly in single threaded mode. The problem
     // here is that the timer tasks are run via the message loop, and when
     // they run, we've had no chance to construct a DebugScopedSetXXXThread
     // object. The result is that we report that we're running on the main
     // thread. In multi-threaded mode, this timer is run on the compositor
     // thread, so to keep this consistent in single-threaded mode, we'll
@@ skipping 3280 matching lines @@
 }
 
 void LayerTreeHostImpl::UnregisterPictureLayerImpl(PictureLayerImpl* layer) {
   std::vector<PictureLayerImpl*>::iterator it =
       std::find(picture_layers_.begin(), picture_layers_.end(), layer);
   DCHECK(it != picture_layers_.end());
   picture_layers_.erase(it);
 }
 
 }  // namespace cc