Send extension console messages to the right WebFrame.

extensions/renderer/resources/uncaught_exception_handler.js

 // Copyright 2014 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.
 
 // Handles uncaught exceptions thrown by extensions. By default this is to
 // log an error message, but tests may override this behaviour.
 var handler = function(message, e) {
-  console.error(message);
+  window.console.error(message);

[not at google - send to devlin, 2014/10/28 16:00:41]

The use of console rather than window.console here is deliberate. We've seen
extensions overriding window.console and breaking us.

These messages are supposed to be going via blink -
https://code.google.com/p/chromium/codesearch#chromium/src/extensions/rendere...
- so something must have gone wrong in that process.

 };
 
 /**
  * Append the error description and stack trace to |message|.
  *
  * @param {string} message - The prefix of the error message.
  * @param {Error|*} e - The thrown error object. This object is potentially
  *   unsafe, because it could be generated by an extension.
  * @param {string=} priorStackTrace - The stack trace to be appended to the
  *   error message. This stack trace must not include stack frames of |e.stack|,
@@ skipping 82 matching lines @@
 };
 
 // |newHandler| A function which matches |handler|.
 exports.setHandler = function(newHandler) {
   handler = newHandler;
 };
 
 exports.getStackTrace = getStackTrace;
 exports.getExtensionStackTrace = getExtensionStackTrace;
 exports.safeErrorToString = safeErrorToString;