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

tools/perf/metrics/gpu_rendering_stats.py

 # Copyright 2013 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.
 
 class GpuRenderingStats(object):
   def __init__(self, rendering_stats_deltas):
     rs = rendering_stats_deltas
 
     # Scroll Stats
     self.total_time = rs.get('totalTimeInSeconds', 0)
@@ skipping 27 matching lines @@
 
     # Latency Stats
     self.input_event_count = rs.get('inputEventCount', 0)
     self.input_event_latency = rs.get('totalInputLatency', 0)
     self.touch_ui_count = rs.get('touchUICount', 0)
     self.touch_ui_latency = rs.get('totalTouchUILatency', 0)
     self.touch_acked_count = rs.get('touchAckedCount', 0)
     self.touch_acked_latency = rs.get('totalTouchAckedLatency', 0)
     self.scroll_update_count = rs.get('scrollUpdateCount', 0)
     self.scroll_update_latency = rs.get('totalScrollUpdateLatency', 0)
+    self.impl_to_main_touch_event_count = rs.get('implToMainTouchEventCount', 0)
+    self.total_impl_to_main_touch_event_latency = rs.get(
+        'totalImplToMainTouchEventLatency', 0)
+    self.impl_to_main_gesture_scroll_event_count = rs.get(
+        'implToMainGestureScrollEventCount', 0)
+    self.total_impl_to_main_gesture_scroll_event_latency = rs.get(
+        'totalImplToMainGestureScrollEventLatency', 0)