cc: Use commit to activation time in repaint HUD

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 1853 matching lines @@
     client_->RenewTreePriority();
 
   client_->OnCanDrawStateChanged(CanDraw());
   client_->DidActivateSyncTree();
   if (!tree_activation_callback_.is_null())
     tree_activation_callback_.Run();
 
   if (debug_state_.continuous_painting) {
     const RenderingStats& stats =
         rendering_stats_instrumentation_->GetRenderingStats();
-    paint_time_counter_->SavePaintTime(stats.main_stats.paint_time +

[brianderson, 2014/10/29 00:24:15]

What is main_stats.paint_time?

[ernstm, 2014/10/29 17:21:19]

paint_time was a pre-impl-side painting metric, originally used for the legacy
software mode. The last call site that records it is
cc/resources/bitmap_content_layer_updater.cc:83 which is dead code according to
Dana. We should remove paint_time from rendering_stats and the telemetry side as
well; maybe as a separate patch?

-                                       stats.main_stats.record_time +
-                                       stats.impl_stats.rasterize_time);
+    paint_time_counter_->SavePaintTime(
+        stats.impl_stats.commit_to_activate_duration.GetLastTimeDelta());
   }
 
   if (time_source_client_adapter_ && time_source_client_adapter_->Active())
     DCHECK(active_tree_->root_layer());
 
   scoped_ptr<PageScaleAnimation> page_scale_animation =
       active_tree_->TakePageScaleAnimation();
   if (page_scale_animation) {
     page_scale_animation_ = page_scale_animation.Pass();
     SetNeedsAnimate();
@@ skipping 1593 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