Refactor all video related processing to its own class

tools/perf/metrics/speedindex_unittest.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.
 
 # These tests access private methods in the speedindex module.
 # pylint: disable=W0212
 
 import json
 import os
 import unittest
@@ skipping 18 matching lines @@
   def __init__(self):
     self._events = []
 
   def SetAllEvents(self, events):
     self._events = events
 
   def GetAllEvents(self):
     return self._events
 
 
+class FakeVideo(object):
+
+  def __init__(self, frames):
+    self._frames = frames
+
+  def GetVideoFrameIter(self):
+    for frame in self._frames:
+      yield frame
+
 class FakeBitmap(object):
 
   def __init__(self, r, g, b):
     self._histogram = bitmap.ColorHistogram(r, g, b, bitmap.WHITE)
 
   # pylint: disable=W0613
   def ColorHistogram(self, ignore_color=None, tolerance=None):
     return self._histogram
 
 
 class FakeTab(object):
 
   def __init__(self, video_capture_result=None):
     self._timeline_model = FakeTimelineModel()
     self._javascript_result = None
-    self._video_capture_result = video_capture_result
+    self._video_capture_result = FakeVideo(video_capture_result)
 
   @property
   def timeline_model(self):
     return self._timeline_model
 
   @property
   def video_capture_supported(self):
     return self._video_capture_result is not None
 
   def SetEvaluateJavaScriptResult(self, result):
@@ skipping 150 matching lines @@
 
   def test2ch(self):
     # Page: http://2ch.net/
     # This page has several paint events, including nested paint events.
     self._TestJsonTimelineExpectation(
         '2ch_repeat_timeline.json', (997, 650), 674.58)
 
 
 if __name__ == "__main__":
   unittest.main()