Hide console log messages for imported WPT tests

content/shell/test_runner/web_test_delegate.h

Index: content/shell/test_runner/web_test_delegate.h
diff --git a/content/shell/test_runner/web_test_delegate.h b/content/shell/test_runner/web_test_delegate.h
index 53f803e46e37b0ba130992092125ab365cd5fff0..bfb3938d04639faaa95ce53f4706c0e3993adcef 100644
--- a/content/shell/test_runner/web_test_delegate.h
+++ b/content/shell/test_runner/web_test_delegate.h
@@ -70,6 +70,10 @@ class WebTestDelegate {
   virtual void SetDeviceOrientationData(
       const blink::WebDeviceOrientationData& data) = 0;
 
+  // Add a message to stderr (not saved to expected output files, for debugging
+  // only).
+  virtual void PrintStderrMessage(const std::string& message) = 0;

[dcheng, 2017/03/09 21:38:36]

FWIW, I'd call this PrintMessageToStderr (along with all the related support
stuff)

+
   // Add a message to the text dump for the layout test.
   virtual void PrintMessage(const std::string& message) = 0;