Made the hardware_accelerated_feature test dump page content on failure.

content/test/gpu/gpu_tests/hardware_accelerated_feature.py

Index: content/test/gpu/gpu_tests/hardware_accelerated_feature.py
diff --git a/content/test/gpu/gpu_tests/hardware_accelerated_feature.py b/content/test/gpu/gpu_tests/hardware_accelerated_feature.py
index 2680df1744f86ed7ccf7368421de0f913440edde..45253c478b4477b82ecb27b670f272e96a33f0e2 100644
--- a/content/test/gpu/gpu_tests/hardware_accelerated_feature.py
+++ b/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):