telemetry: Add GetRendererProcessFromTab to timeline model.

tools/perf/metrics/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.
 
 from operator import attrgetter
 
-RENDER_PROCESS_MARKER = 'RenderProcessMarker'
-
 
 class RenderingStats(object):
-  def __init__(self, render_process_marker, timeline_markers):
+  def __init__(self, renderer_process, timeline_markers):
     """
     Utility class for extracting rendering statistics from the timeline (or
     other loggin facilities), and providing them in a common format to classes
     that compute benchmark metrics from this data.
 
     Stats can either be numbers, or lists of numbers. Classes that calculate
     metrics from the stats must be able to handle both cases. The length of
     different list stats may vary.
 
     All *_time values are measured in milliseconds.
     """
-    assert(len(render_process_marker) == 1)
     assert(len(timeline_markers) > 0)
-    self.renderer_process = render_process_marker[0].start_thread.parent
+    self.renderer_process = renderer_process
     self.start = timeline_markers[0].start
     self.end = timeline_markers[-1].start + timeline_markers[-1].duration
 
     self.frame_count = []
     self.frame_timestamps = []
     self.frame_times = []
     self.paint_time = []
     self.painted_pixel_count = []
     self.record_time = []
     self.recorded_pixel_count = []
@@ skipping 78 matching lines @@
         self.frame_timestamps.append(
             event.start)
         if not first_frame:
           self.frame_times.append(round(self.frame_timestamps[-1] -
                                         self.frame_timestamps[-2], 2))
         first_frame = False
       self.rasterize_time.append(1000.0 *
           event.args['data']['rasterize_time'])
       self.rasterized_pixel_count.append(
           event.args['data']['rasterized_pixel_count'])