cc: Use commit to activation time in repaint HUD

cc/trees/layer_tree_host_impl.cc

Index: cc/trees/layer_tree_host_impl.cc
diff --git a/cc/trees/layer_tree_host_impl.cc b/cc/trees/layer_tree_host_impl.cc
index be9fd58282b19b90a93fd6e3d261c7a5bdafc131..19b4c18e46ef399a21f48372657a78fe150f1553 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -1871,9 +1871,8 @@ void LayerTreeHostImpl::ActivateSyncTree() {
   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())