re-land: Use browser compositor rendering stats in smoothness

tools/perf/metrics/rendering_stats.py

Index: tools/perf/metrics/rendering_stats.py
diff --git a/tools/perf/metrics/rendering_stats.py b/tools/perf/metrics/rendering_stats.py
index 0c176b4b740e1694ac44daae133d88e691ebf00c..ba987327ef79e17dddb550aa0bc82648ac88ac88 100644
--- a/tools/perf/metrics/rendering_stats.py
+++ b/tools/perf/metrics/rendering_stats.py
@@ -15,6 +15,7 @@ BEGIN_COMP_NAME = 'INPUT_EVENT_LATENCY_BEGIN_RWH_COMPONENT'
 # This is when the input event has reached swap buffer.
 END_COMP_NAME = 'INPUT_EVENT_LATENCY_TERMINATED_FRAME_SWAP_COMPONENT'
 
+
 def GetScrollInputLatencyEvents(scroll_type, browser_process, timeline_range):
   """Get scroll events' LatencyInfo from the browser process's trace buffer
      that are within the timeline_range.
@@ -39,6 +40,7 @@ def GetScrollInputLatencyEvents(scroll_type, browser_process, timeline_range):
           scroll_events.append(ss)
   return scroll_events
 
+
 def ComputeMouseWheelScrollLatency(mouse_wheel_events):
   """ Compute the mouse wheel scroll latency.
 
@@ -57,6 +59,7 @@ def ComputeMouseWheelScrollLatency(mouse_wheel_events):
       mouse_wheel_latency.append(latency / 1000.0)
   return mouse_wheel_latency
 
+
 def ComputeTouchScrollLatency(touch_scroll_events):
   """ Compute the touch scroll latency.
 
@@ -83,6 +86,24 @@ def ComputeTouchScrollLatency(touch_scroll_events):
         touch_scroll_latency.append(latency / 1000.0)
   return touch_scroll_latency
 
+
+def HasRenderingStats(process):
+  """ Returns True if the process contains at least one
+      BenchmarkInstrumentation::*RenderingStats event with a frame.
+  """
+  if not process:
+    return False
+  for event in process.IterAllSlicesOfName(
+      'BenchmarkInstrumentation::MainThreadRenderingStats'):
+    if 'data' in event.args and event.args['data']['frame_count'] == 1:
+      return True
+  for event in process.IterAllSlicesOfName(
+      'BenchmarkInstrumentation::ImplThreadRenderingStats'):
+    if 'data' in event.args and event.args['data']['frame_count'] == 1:
+      return True
+  return False
+
+
 class RenderingStats(object):
   def __init__(self, renderer_process, browser_process, timeline_ranges):
     """
@@ -96,7 +117,11 @@ class RenderingStats(object):
     All *_time values are measured in milliseconds.
     """
     assert(len(timeline_ranges) > 0)
-    self.renderer_process = renderer_process
+    # Find the top level process with rendering stats (browser or renderer).
+    if HasRenderingStats(browser_process):
+      self.top_level_process = browser_process
+    else:
+      self.top_level_process  = renderer_process
 
     self.frame_timestamps = []
     self.frame_times = []
@@ -153,7 +178,7 @@ class RenderingStats(object):
   def initMainThreadStatsFromTimeline(self, timeline_range):
     event_name = 'BenchmarkInstrumentation::MainThreadRenderingStats'
     events = []
-    for event in self.renderer_process.IterAllSlicesOfName(event_name):
+    for event in self.top_level_process.IterAllSlicesOfName(event_name):
       if event.start >= timeline_range.min and event.end <= timeline_range.max:
         if 'data' not in event.args:
           continue
@@ -184,7 +209,7 @@ class RenderingStats(object):
   def initImplThreadStatsFromTimeline(self, timeline_range):
     event_name = 'BenchmarkInstrumentation::ImplThreadRenderingStats'
     events = []
-    for event in self.renderer_process.IterAllSlicesOfName(event_name):
+    for event in self.top_level_process.IterAllSlicesOfName(event_name):
       if event.start >= timeline_range.min and event.end <= timeline_range.max:
         if 'data' not in event.args:
           continue