telemetry: handle tests that are not supported on a platform.

tools/perf/measurements/rasterize_and_record_micro.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.
 
 import sys
 import time
 
 from telemetry.core.util import TimeoutException
 from telemetry.page import page_measurement
+from telemetry.page import page_test
 
 class RasterizeAndRecordMicro(page_measurement.PageMeasurement):
   def __init__(self):
     super(RasterizeAndRecordMicro, self).__init__('', True)
+    self._compositing_features_enabled = False
 
   def AddCommandLineOptions(self, parser):
     parser.add_option('--start-wait-time', dest='start_wait_time',
                       default=2,
                       help='Wait time before the benchmark is started ' +
                       '(must be long enought to load all content)')
     parser.add_option('--rasterize-repeat', dest='rasterize_repeat',
                       default=100,
                       help='Repeat each raster this many times. Increase ' +
                       'this value to reduce variance.')
     parser.add_option('--record-repeat', dest='record_repeat',
                       default=100,
                       help='Repeat each record this many times. Increase ' +
                       'this value to reduce variance.')
     parser.add_option('--timeout', dest='timeout',
                       default=120,
                       help='The length of time to wait for the micro ' +
                       'benchmark to finish, expressed in seconds.')
 
   def CustomizeBrowserOptions(self, options):
     options.AppendExtraBrowserArgs([
         '--enable-impl-side-painting',
         '--force-compositing-mode',
         '--enable-threaded-compositing',
         '--enable-gpu-benchmarking'
     ])
 
+  def DidStartBrowser(self, browser):
+    # Check if the we actually have threaded forced compositing enabled.

[vmpstr, 2013/12/20 23:20:10]

nit: s/the // and possibly s/forced //

+    system_info = browser.GetSystemInfo()
+    if (system_info.gpu.feature_status
+        and system_info.gpu.feature_status.get(

[vmpstr, 2013/12/20 23:20:10]

nit: I don't really know the (chromium) python style.. should "and" be at the
end of the previous line? It seems to be more consistent with if around line 61

+            'compositing', None) == 'enabled_force_threaded'):

[vmpstr, 2013/12/20 23:20:10]

I think None is not needed here, assuming feature_status is a dict

+      self._compositing_features_enabled = True
+
   def MeasurePage(self, page, tab, results):
+    # Throw an exception if threaded forced compositing is not enabled.
+    if (not self._compositing_features_enabled):
+      raise page_test.TestNotSupportedOnPlatformFailure(
+          'Compositing feature status unknown or not '+
+          'forced and threaded. Skipping measurement.')
+
     # TODO(vmpstr): Remove this temporary workaround when reference build has
     # been updated to branch 1713 or later.
     backend = tab.browser._browser_backend # pylint: disable=W0212
     if (not hasattr(backend, 'chrome_branch_number') or
         (sys.platform != 'android' and backend.chrome_branch_number < 1713)):
-      print ('Warning: rasterize_and_record_micro requires Chrome branch 1713 '
-             'or later. Skipping measurement.')
-      sys.exit(0)
+      raise page_test.TestNotSupportedOnPlatformFailure(
+          'rasterize_and_record_micro requires Chrome branch 1713 '
+          'or later. Skipping measurement.')
 
     try:
       tab.WaitForJavaScriptExpression("document.readyState == 'complete'", 10)
     except TimeoutException:
       pass
     time.sleep(float(self.options.start_wait_time))
 
     record_repeat = self.options.record_repeat
     rasterize_repeat = self.options.rasterize_repeat
     # Enqueue benchmark
@@ skipping 24 matching lines @@
 
     pixels_recorded = data['pixels_recorded']
     record_time = data['record_time_ms']
     pixels_rasterized = data['pixels_rasterized']
     rasterize_time = data['rasterize_time_ms']
 
     results.Add('pixels_recorded', '', pixels_recorded)
     results.Add('record_time', 'ms', record_time)
     results.Add('pixels_rasterized', '', pixels_rasterized)
     results.Add('rasterize_time', 'ms', rasterize_time)
-