Change DtmfSenderHandler to handle events on the signaling thread.

content/renderer/media/rtc_dtmf_sender_handler.h

Index: content/renderer/media/rtc_dtmf_sender_handler.h
diff --git a/content/renderer/media/rtc_dtmf_sender_handler.h b/content/renderer/media/rtc_dtmf_sender_handler.h
index 71271505c6c98ad19c2c13561936cc53d703fd0b..eecad4b898e1b809c58e079f3970757aa2313b79 100644
--- a/content/renderer/media/rtc_dtmf_sender_handler.h
+++ b/content/renderer/media/rtc_dtmf_sender_handler.h
@@ -8,6 +8,7 @@
 #include <string>
 
 #include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
 #include "base/threading/non_thread_safe.h"
 #include "content/common/content_export.h"
 #include "third_party/WebKit/public/platform/WebRTCDTMFSenderHandler.h"
@@ -24,26 +25,29 @@ namespace content {
 // occur on the main render thread.
 class CONTENT_EXPORT RtcDtmfSenderHandler
     : NON_EXPORTED_BASE(public blink::WebRTCDTMFSenderHandler),
-      NON_EXPORTED_BASE(public webrtc::DtmfSenderObserverInterface),
       NON_EXPORTED_BASE(public base::NonThreadSafe) {
  public:
   explicit RtcDtmfSenderHandler(webrtc::DtmfSenderInterface* dtmf_sender);
   virtual ~RtcDtmfSenderHandler();
 
   // blink::WebRTCDTMFSenderHandler implementation.
-  virtual void setClient(
+  void setClient(
       blink::WebRTCDTMFSenderHandlerClient* client) override;
-  virtual blink::WebString currentToneBuffer() override;
-  virtual bool canInsertDTMF() override;
-  virtual bool insertDTMF(const blink::WebString& tones, long duration,
+  blink::WebString currentToneBuffer() override;
+  bool canInsertDTMF() override;
+  bool insertDTMF(const blink::WebString& tones, long duration,
                           long interToneGap) override;
 
-  // webrtc::DtmfSenderObserverInterface implementation.
-  void OnToneChange(const std::string& tone) override;
+  void OnToneChange(const std::string& tone);
 
  private:
   scoped_refptr<webrtc::DtmfSenderInterface> dtmf_sender_;
   blink::WebRTCDTMFSenderHandlerClient* webkit_client_;
+  base::WeakPtrFactory<RtcDtmfSenderHandler> weak_factory_;
+  class Observer;
+  scoped_refptr<Observer> observer_;  // must be after weak_factory_
+
+  DISALLOW_COPY_AND_ASSIGN(RtcDtmfSenderHandler);
 };
 
 }  // namespace content