Fix issue of localDescription and remoteDescription getter.

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 bf040004b0b42800cbc8daa0bbb574c116439bfa..677efb175c87cb530423c6061bb1e7168126196e 100644
--- a/Source/modules/mediastream/RTCPeerConnection.h
+++ b/Source/modules/mediastream/RTCPeerConnection.h
@@ -71,10 +71,10 @@ public:
     void createAnswer(RTCSessionDescriptionCallback*, RTCErrorCallback*, const Dictionary&, ExceptionState&);
 
     void setLocalDescription(RTCSessionDescription*, VoidCallback*, RTCErrorCallback*, ExceptionState&);
-    RTCSessionDescription* localDescription(ExceptionState&);
+    RTCSessionDescription* localDescription();
 
     void setRemoteDescription(RTCSessionDescription*, VoidCallback*, RTCErrorCallback*, ExceptionState&);
-    RTCSessionDescription* remoteDescription(ExceptionState&);
+    RTCSessionDescription* remoteDescription();
 
     String signalingState() const;
 
@@ -110,6 +110,8 @@ public:
     // We allow getStats after close, but not other calls or callbacks.
     bool shouldFireDefaultCallbacks() { return !m_closed && !m_stopped; }
     bool shouldFireGetStatsCallback() { return !m_stopped; }
+    void updateLocalSessionDescriptionIfNeeded(bool pending);
+    void updateRemoteSessionDescriptionIfNeeded(bool pending);
 
     DEFINE_ATTRIBUTE_EVENT_LISTENER(negotiationneeded);
     DEFINE_ATTRIBUTE_EVENT_LISTENER(icecandidate);
@@ -164,6 +166,11 @@ private:
 
     void closeInternal();
 
+    Member<RTCSessionDescription> m_localDescription;
+    Member<RTCSessionDescription> m_remoteDescription;
+    Member<RTCSessionDescription> m_pendingLocalDescription;
+    Member<RTCSessionDescription> m_pendingRemoteDescription;
+
     SignalingState m_signalingState;
     ICEGatheringState m_iceGatheringState;
     ICEConnectionState m_iceConnectionState;