Implement TTS dispatcher using RenderProcessObserver instead of MessageFilter.

chrome/renderer/tts_dispatcher.h

Index: chrome/renderer/tts_dispatcher.h
diff --git a/chrome/renderer/tts_dispatcher.h b/chrome/renderer/tts_dispatcher.h
index 77433e71df50c1a2f63213808a159a08f5a75100..bbebe6d920a65da89401ca8f6caa1e191b8fca78 100644
--- a/chrome/renderer/tts_dispatcher.h
+++ b/chrome/renderer/tts_dispatcher.h
@@ -8,13 +8,16 @@
 #include <vector>
 
 #include "base/basictypes.h"
+#include "base/compiler_specific.h"
 #include "base/hash_tables.h"
-#include "content/public/renderer/render_view.h"
-#include "ipc/ipc_channel_proxy.h"
+#include "content/public/renderer/render_process_observer.h"
 #include "third_party/WebKit/Source/Platform/chromium/public/WebSpeechSynthesizer.h"
 #include "third_party/WebKit/Source/Platform/chromium/public/WebSpeechSynthesizerClient.h"
 
-class RenderViewImpl;
+namespace IPC {
+class Message;
+}
+
 struct TtsVoice;
 
 // TtsDispatcher is a delegate for methods used by WebKit for
@@ -22,15 +25,15 @@ struct TtsVoice;
 // TtsDispatcherHost (owned by RenderViewHost).
 class TtsDispatcher
     : public WebKit::WebSpeechSynthesizer,
-      public IPC::ChannelProxy::MessageFilter {
+      public content::RenderProcessObserver {
  public:
   explicit TtsDispatcher(WebKit::WebSpeechSynthesizerClient* client);
 
  private:
   virtual ~TtsDispatcher();
 
-  // IPC::ChannelProxy::MessageFilter override.
-  virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
+  // RenderProcessObserver override.
+  virtual bool OnControlMessageReceived(const IPC::Message& message) OVERRIDE;
 
   // WebKit::WebSpeechSynthesizer implementation.
   virtual void updateVoiceList() OVERRIDE;
@@ -59,11 +62,6 @@ class TtsDispatcher
   // Weak reference, this will be valid as long as this object exists.
   WebKit::WebSpeechSynthesizerClient* synthesizer_client_;
 
-  // Message loop for the main render thread. Utilized to
-  // ensure that callbacks into WebKit happen on the main thread
-  // instead of the originating IO thread.
-  scoped_refptr<base::MessageLoopProxy> main_loop_;
-
   // Next utterance id, used to map response IPCs to utterance objects.
   static int next_utterance_id_;