Implement web speech synthesis.

chrome/browser/speech/tts_message_filter.h

+// Copyright (c) 2013 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 CHROME_BROWSER_SPEECH_TTS_MESSAGE_FILTER_H_
+#define CHROME_BROWSER_SPEECH_TTS_MESSAGE_FILTER_H_
+
+#include "content/public/browser/browser_message_filter.h"
+
+// A message filter implementation that receives text-to-speech requests.
+class TtsMessageFilter : public content::BrowserMessageFilter {
+ public:
+  explicit TtsMessageFilter(int render_process_id);
+
+  // content::BrowserMessageFilter implementation.
+  virtual void OverrideThreadForMessage(
+      const IPC::Message& message,
+      content::BrowserThread::ID* thread) OVERRIDE;
+  virtual bool OnMessageReceived(const IPC::Message& message,
+                                 bool* message_was_ok) OVERRIDE;
+
+ private:
+  virtual ~TtsMessageFilter();
+  int render_process_id_;
+  int route_id_;
+  int identifier_;
+};
+
+#endif  // CHROME_BROWSER_SPEECH_TTS_MESSAGE_FILTER_H_