Fix a few spelling errors in comments.

content/public/test/javascript_test_observer.h

 // 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.
 
 #ifndef CONTENT_PUBLIC_TEST_JAVASCRIPT_TEST_OBSERVER_H_
 #define CONTENT_PUBLIC_TEST_JAVASCRIPT_TEST_OBSERVER_H_
 
 #include <string>
 
 #include "base/compiler_specific.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 
 namespace base {
 class DictionaryValue;
 }
 
 namespace content {
 class WebContents;
 
 // Base class for handling a stream of automation messages produced by a
 // JavascriptTestObserver.
 class TestMessageHandler {
  public:
   enum MessageResponse {
     // Reset the timeout and keep running.
     CONTINUE,
-    // Stop runnning.
+    // Stop running.
     DONE
   };
 
   TestMessageHandler();
   virtual ~TestMessageHandler();
 
   // Called when a message is received from the DOM automation controller.
   virtual MessageResponse HandleMessage(const std::string& json) = 0;
 
   void SetError(const std::string& message);
@@ skipping 49 matching lines @@
   bool running_;
   bool finished_;
   NotificationRegistrar registrar_;
 
   DISALLOW_COPY_AND_ASSIGN(JavascriptTestObserver);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_TEST_JAVASCRIPT_TEST_OBSERVER_H_