Adding GetConfiguration to PeerConnection.

Just returns the configuration the PC was constructed with, or the last
one passed into SetConfiguration.

BUG=chromium:587453

Review-Url: https://codereview.webrtc.org/2504103002
Cr-Commit-Position: refs/heads/master@{#15111}
diff --git a/webrtc/api/peerconnection.h b/webrtc/api/peerconnection.h
index f444eb7..70fd867 100644
--- a/webrtc/api/peerconnection.h
+++ b/webrtc/api/peerconnection.h
@@ -129,6 +129,7 @@
                            SessionDescriptionInterface* desc) override;
   void SetRemoteDescription(SetSessionDescriptionObserver* observer,
                             SessionDescriptionInterface* desc) override;
+  PeerConnectionInterface::RTCConfiguration GetConfiguration() override;
   bool SetConfiguration(
       const PeerConnectionInterface::RTCConfiguration& configuration) override;
   bool AddIceCandidate(const IceCandidateInterface* candidate) override;
@@ -389,6 +390,7 @@
   SignalingState signaling_state_;
   IceConnectionState ice_connection_state_;
   IceGatheringState ice_gathering_state_;
+  PeerConnectionInterface::RTCConfiguration configuration_;
 
   std::unique_ptr<cricket::PortAllocator> port_allocator_;
   // The EventLog needs to outlive the media controller.
@@ -420,8 +422,6 @@
 
   bool remote_peer_supports_msid_ = false;
 
-  bool enable_ice_renomination_ = false;
-
   std::vector<rtc::scoped_refptr<RtpSenderProxyWithInternal<RtpSenderInternal>>>
       senders_;
   std::vector<