NotEnoughFramesError no longer raises an exception.

tools/telemetry/telemetry/web_perf/metrics/rendering_stats_unittest.py

 # Copyright 2014 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.
 
 import random
 import unittest
 
 import telemetry.timeline.async_slice as tracing_async_slice
 import telemetry.timeline.bounds as timeline_bounds
 from telemetry.perf_tests_helper import FlattenList
 from telemetry.timeline import model
 from telemetry.util.statistics import DivideIfPossibleOrZero
 from telemetry.web_perf.metrics.rendering_stats import (
     BEGIN_COMP_NAME,
     BEGIN_SCROLL_UPDATE_COMP_NAME,
     END_COMP_NAME,
     FORWARD_SCROLL_UPDATE_COMP_NAME,
     GESTURE_SCROLL_UPDATE_EVENT_NAME,
     ORIGINAL_COMP_NAME,
     SCROLL_UPDATE_EVENT_NAME,
     UI_COMP_NAME)
 from telemetry.web_perf.metrics.rendering_stats import (
     ComputeInputEventLatencies)
 from telemetry.web_perf.metrics.rendering_stats import GetInputLatencyEvents
 from telemetry.web_perf.metrics.rendering_stats import HasRenderingStats
-from telemetry.web_perf.metrics.rendering_stats import NotEnoughFramesError
 from telemetry.web_perf.metrics.rendering_stats import RenderingStats
 
 
 class MockTimer(object):
   """A mock timer class which can generate random durations.
 
   An instance of this class is used as a global timer to generate random
   durations for stats and consistent timestamps for all mock trace events.
   The unit of time is milliseconds.
   """
@@ skipping 258 matching lines @@
     timer.Advance(2, 4)
     renderer_main.BeginSlice('webkit.console', 'ActionB', timer.Get(), '')
     timer.Advance(2, 4)
     renderer_main.EndSlice(timer.Get())
 
     renderer.FinalizeImport()
 
     timeline_markers = timeline.FindTimelineMarkers(['ActionA', 'ActionB'])
     timeline_ranges = [ timeline_bounds.Bounds.CreateFromEvent(marker)
                         for marker in timeline_markers ]
-    self.assertRaises(NotEnoughFramesError, RenderingStats,
-                      renderer, None, timeline_ranges)
+
+    stats = RenderingStats(renderer, None, timeline_ranges)
+    self.assertEquals(0, len(stats.frame_timestamps[1]))
+
 
   def testFromTimeline(self):
     timeline = model.TimelineModel()
 
     # Create a browser process and a renderer process, and a main thread and
     # impl thread for each.
     browser = timeline.GetOrCreateProcess(pid = 1)
     browser_main = browser.GetOrCreateThread(tid = 11)
     browser_compositor = browser.GetOrCreateThread(tid = 12)
     renderer = timeline.GetOrCreateProcess(pid = 2)
@@ skipping 154 matching lines @@
     stats = RenderingStats(renderer, browser, timeline_ranges)
     self.assertEquals(FlattenList(stats.input_event_latency), [
         latency for name, latency in ref_latency.input_event_latency
         if name != SCROLL_UPDATE_EVENT_NAME])
     self.assertEquals(FlattenList(stats.scroll_update_latency), [
         latency for name, latency in ref_latency.input_event_latency
         if name == SCROLL_UPDATE_EVENT_NAME])
     self.assertEquals(FlattenList(stats.gesture_scroll_update_latency), [
         latency for name, latency in ref_latency.input_event_latency
         if name == GESTURE_SCROLL_UPDATE_EVENT_NAME])