Add method to notify blink when PeerConnection is closed in Chrome

Source/modules/mediastream/RTCPeerConnection.h

Index: Source/modules/mediastream/RTCPeerConnection.h
diff --git a/Source/modules/mediastream/RTCPeerConnection.h b/Source/modules/mediastream/RTCPeerConnection.h
index 34d4afcb1883c6ec357d8db633368cd17a0b89a1..e3ca9d04f2c36c443208af0a3d30dd4d4f38708f 100644
--- a/Source/modules/mediastream/RTCPeerConnection.h
+++ b/Source/modules/mediastream/RTCPeerConnection.h
@@ -129,6 +129,7 @@ public:
     virtual void didRemoveRemoteStream(const WebMediaStream&) OVERRIDE;
     virtual void didAddRemoteDataChannel(WebRTCDataChannelHandler*) OVERRIDE;
     virtual void releasePeerConnectionHandler() OVERRIDE;
+    virtual void closePeerConnection() OVERRIDE;
 
     // EventTarget
     virtual const AtomicString& interfaceName() const OVERRIDE;
@@ -160,6 +161,8 @@ private:
     void changeIceGatheringState(WebRTCPeerConnectionHandlerClient::ICEGatheringState);
     void changeIceConnectionState(WebRTCPeerConnectionHandlerClient::ICEConnectionState);
 
+    void closeInternal();
+
     SignalingState m_signalingState;
     ICEGatheringState m_iceGatheringState;
     ICEConnectionState m_iceConnectionState;