Create the API that returns the RTCConfiguration of the PeerConnection.

components/test_runner/mock_webrtc_peer_connection_handler.cc

Index: components/test_runner/mock_webrtc_peer_connection_handler.cc
diff --git a/components/test_runner/mock_webrtc_peer_connection_handler.cc b/components/test_runner/mock_webrtc_peer_connection_handler.cc
index 0b79863f1d454fc15fc56ba96378e8a71e8f8613..c600776909b92336e5f2df5f07d560c22a606378 100644
--- a/components/test_runner/mock_webrtc_peer_connection_handler.cc
+++ b/components/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"
@@ -459,6 +460,11 @@ WebRTCErrorType MockWebRTCPeerConnectionHandler::setConfiguration(
   return WebRTCErrorType::kNone;
 }
 
+blink::WebRTCConfiguration MockWebRTCPeerConnectionHandler::getConfiguration() {
+  blink::WebRTCConfiguration blink_config;
+  return blink_config;
+}
+
 bool MockWebRTCPeerConnectionHandler::addICECandidate(
     const WebRTCICECandidate& ice_candidate) {
   client_->didGenerateICECandidate(ice_candidate);