Made the hardware_accelerated_feature test dump page content on failure.

BUG=396385
R=kbr@chromium.org

Review URL: https://codereview.chromium.org/406143003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@285025 0039d316-1c4b-4281-b951-d872f2087c98

content/test/gpu/gpu_tests/hardware_accelerated_feature.py

@@ -29,6 +29,8 @@ 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):