Add Needed Forward Declaration

content/shell/renderer/test_runner/mock_web_speech_recognizer.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_SHELL_RENDERER_TEST_RUNNER_MOCK_WEB_SPEECH_RECOGNIZER_H_
 #define CONTENT_SHELL_RENDERER_TEST_RUNNER_MOCK_WEB_SPEECH_RECOGNIZER_H_
 
 #include <deque>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "content/shell/renderer/test_runner/web_task.h"
 #include "third_party/WebKit/public/web/WebSpeechRecognizer.h"
 
 namespace blink {
 class WebSpeechRecognitionHandle;
 class WebSpeechRecognitionParams;
 class WebSpeechRecognizerClient;
+class WebString;
 }
 
 namespace content {
 
 class WebTestDelegate;
 
 class MockWebSpeechRecognizer : public blink::WebSpeechRecognizer {
  public:
   MockWebSpeechRecognizer();
   virtual ~MockWebSpeechRecognizer();
@@ skipping 59 matching lines @@
    private:
     DISALLOW_COPY_AND_ASSIGN(StepTask);
   };
 
   DISALLOW_COPY_AND_ASSIGN(MockWebSpeechRecognizer);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_SHELL_RENDERER_TEST_RUNNER_MOCK_WEB_SPEECH_RECOGNIZER_H_