Add telemetry to track the time an event spent waiting for the main thread.

cc/debug/rendering_stats.cc

 // Copyright 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 "cc/debug/rendering_stats.h"
 
 namespace cc {
 
 RenderingStats::RenderingStats()
     : animation_frame_count(0),
@@ skipping 46 matching lines @@
   enumerator->AddInt64("totalDeferredImageCacheHitCount",
                        total_deferred_image_cache_hit_count);
   enumerator->AddInt64("totalImageGatheringCount",
                        total_image_gathering_count);
   enumerator->AddDouble("totalDeferredImageDecodeTimeInSeconds",
                         total_deferred_image_decode_time.InSecondsF());
   enumerator->AddDouble("totalImageGatheringTimeInSeconds",
                         total_image_gathering_time.InSecondsF());
   enumerator->AddDouble("totalTileAnalysisTimeInSeconds",
                         total_tile_analysis_time.InSecondsF());
+  enumerator->AddDouble("averageImplThreadToMainThreadTime",
+                        average_impl_thread_to_main_thread_time.InSecondsF());
 }
 
 void RenderingStats::Add(const RenderingStats& other) {
   animation_frame_count += other.animation_frame_count;
   screen_frame_count += other.screen_frame_count;
   dropped_frame_count += other.dropped_frame_count;
   total_paint_time += other.total_paint_time;
   total_record_time += other.total_record_time;
   total_rasterize_time += other.total_rasterize_time;
   total_rasterize_time_for_now_bins_on_pending_tree +=
@@ skipping 10 matching lines @@
   num_missing_tiles += other.num_missing_tiles;
   total_deferred_image_decode_count += other.total_deferred_image_decode_count;
   total_deferred_image_cache_hit_count +=
       other.total_deferred_image_cache_hit_count;
   total_image_gathering_count += other.total_image_gathering_count;
   total_deferred_image_decode_time += other.total_deferred_image_decode_time;
   total_image_gathering_time += other.total_image_gathering_time;
   total_tiles_analyzed += other.total_tiles_analyzed;
   solid_color_tiles_analyzed += other.solid_color_tiles_analyzed;
   total_tile_analysis_time += other.total_tile_analysis_time;
+  average_impl_thread_to_main_thread_time +=
+      other.average_impl_thread_to_main_thread_time;
 }
 
 }  // namespace cc