Create the API that returns the RTCConfiguration of the PeerConnection.

content/shell/test_runner/mock_webrtc_peer_connection_handler.cc

Index: content/shell/test_runner/mock_webrtc_peer_connection_handler.cc
diff --git a/content/shell/test_runner/mock_webrtc_peer_connection_handler.cc b/content/shell/test_runner/mock_webrtc_peer_connection_handler.cc
index 078ceaf4d61483292b555133da600847e4e5cc1d..b3a90664ac7ffedd517ced230eea3d9bd639282d 100644
--- a/content/shell/test_runner/mock_webrtc_peer_connection_handler.cc
+++ b/content/shell/test_runner/mock_webrtc_peer_connection_handler.cc
@@ -20,6 +20,7 @@
 #include "third_party/WebKit/public/platform/WebMediaStreamSource.h"
 #include "third_party/WebKit/public/platform/WebMediaStreamTrack.h"
 #include "third_party/WebKit/public/platform/WebRTCAnswerOptions.h"
+#include "third_party/WebKit/public/platform/WebRTCConfiguration.h"
 #include "third_party/WebKit/public/platform/WebRTCDataChannelInit.h"
 #include "third_party/WebKit/public/platform/WebRTCOfferOptions.h"
 #include "third_party/WebKit/public/platform/WebRTCPeerConnectionHandlerClient.h"
@@ -442,6 +443,10 @@ WebRTCErrorType MockWebRTCPeerConnectionHandler::setConfiguration(
   return WebRTCErrorType::kNone;
 }
 
+blink::WebRTCConfiguration MockWebRTCPeerConnectionHandler::getConfiguration() {
+  return blink::WebRTCConfiguration();
+}
+
 bool MockWebRTCPeerConnectionHandler::addICECandidate(
     const WebRTCICECandidate& ice_candidate) {
   client_->didGenerateICECandidate(ice_candidate);