Android / Telemetry: make surface_stats_collector more robust.

tools/perf/perf_tools/smoothness_measurement.py

 # Copyright (c) 2012 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 perf_tools import smoothness_metrics
 from telemetry.core import util
 from telemetry.page import page_measurement
 
 class DidNotScrollException(page_measurement.MeasurementFailure):
   def __init__(self):
     super(DidNotScrollException, self).__init__('Page did not scroll')
 
+class MissingDisplayFrameRate(page_measurement.MeasurementFailure):
+  def __init__(self):
+    super(MissingDisplayFrameRate, self).__init__(
+        'Missing display frame rate metrics')
+
 def DivideIfPossibleOrZero(numerator, denominator):
   if denominator == 0:
     return 0
   return numerator / denominator
 
 def CalcScrollResults(rendering_stats_deltas, results):
   num_frames_sent_to_screen = rendering_stats_deltas['numFramesSentToScreen']
 
   mean_frame_time_seconds = (
     rendering_stats_deltas['totalTimeInSeconds'] /
@@ skipping 187 matching lines @@
     CalcImageDecodingResults(rendering_stats_deltas, results)
     CalcAnalysisResults(rendering_stats_deltas, results)
     CalcLatencyResults(rendering_stats_deltas, results)
 
     if self.options.report_all_results:
       for k, v in rendering_stats_deltas.iteritems():
         results.Add(k, '', v)
 
     if tab.browser.platform.IsRawDisplayFrameRateSupported():
       for r in tab.browser.platform.GetRawDisplayFrameRateMeasurements():
+        if not r.value:
+          raise MissingDisplayFrameRate()
         results.Add(r.name, r.unit, r.value)