Made the hardware_accelerated_feature test dump page content on failure.

content/test/gpu/gpu_tests/hardware_accelerated_feature.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 hardware_accelerated_feature_expectations as expectations
 
 from telemetry import benchmark
 from telemetry.page import page as page_module
 from telemetry.page import page_set
 from telemetry.page import page_test
 
@@ skipping 11 matching lines @@
       }
     }
     return false;
   };
 """;
 
 class _HardwareAcceleratedFeatureValidator(page_test.PageTest):
   def ValidatePage(self, page, tab, results):
     feature = page.feature
     if not tab.EvaluateJavaScript('VerifyHardwareAccelerated("%s")' % feature):
+      print 'Test failed. Printing page contents:'
+      print tab.EvaluateJavaScript('document.body.innerHTML')
       raise page_test.Failure('%s not hardware accelerated' % feature)
 
 def safe_feature_name(feature):
   return feature.lower().replace(' ', '_')
 
 class ChromeGpuPage(page_module.Page):
   def __init__(self, page_set, feature):
     super(ChromeGpuPage, self).__init__(
       url='chrome://gpu', page_set=page_set, base_dir=page_set.base_dir,
       name=('HardwareAcceleratedFeature.%s_accelerated' %
             safe_feature_name(feature)))
     self.feature = feature
     self.script_to_evaluate_on_commit = test_harness_script
 
 class HardwareAcceleratedFeature(benchmark.Benchmark):
   """Tests GPU acceleration is reported as active for various features"""
   test = _HardwareAcceleratedFeatureValidator
 
   def CreateExpectations(self, page_set):
     return expectations.HardwareAcceleratedFeatureExpectations()
 
   def CreatePageSet(self, options):
     features = ['WebGL', 'Canvas']
 
     ps = page_set.PageSet(user_agent_type='desktop', file_path='')
 
     for feature in features:
       ps.AddPage(ChromeGpuPage(page_set=ps, feature=feature))
     return ps