Create the API that returns the RTCConfiguration of the PeerConnection.

third_party/WebKit/Source/modules/peerconnection/RTCPeerConnection.cpp

Index: third_party/WebKit/Source/modules/peerconnection/RTCPeerConnection.cpp
diff --git a/third_party/WebKit/Source/modules/peerconnection/RTCPeerConnection.cpp b/third_party/WebKit/Source/modules/peerconnection/RTCPeerConnection.cpp
index 256c5a61800a0b689dc2e7005590e89e9558989c..5c3ea99e1dd25a25081ad7f11088ad1ec6e330e7 100644
--- a/third_party/WebKit/Source/modules/peerconnection/RTCPeerConnection.cpp
+++ b/third_party/WebKit/Source/modules/peerconnection/RTCPeerConnection.cpp
@@ -298,6 +298,7 @@ WebRTCConfiguration parseConfiguration(ExecutionContext* context,
       String username = iceServer.username();
       String credential = iceServer.credential();
 
+      Vector<WebURL> urls;
       for (const String& urlString : urlStrings) {
         KURL url(KURL(), urlString);
         if (!url.isValid()) {
@@ -320,8 +321,10 @@ WebRTCConfiguration parseConfiguration(ExecutionContext* context,
                                            "required when the URL scheme is "
                                            "\"turn\" or \"turns\".");
         }
-        iceServers.push_back(WebRTCIceServer{url, username, credential});
+        urls.push_back(url);
       }
+      WebRTCIceServer webIceServer = {urls, username, credential};
+      iceServers.push_back(webIceServer);
     }
     webConfiguration.iceServers = iceServers;
   }
@@ -795,6 +798,68 @@ RTCSessionDescription* RTCPeerConnection::remoteDescription() {
   return RTCSessionDescription::create(webSessionDescription);
 }
 
+void RTCPeerConnection::getConfiguration(RTCConfiguration& rtcConfig) {
+  blink::WebRTCConfiguration blinkConfig = m_peerHandler->getConfiguration();
+
+  switch (blinkConfig.iceTransportPolicy) {
+    case blink::WebRTCIceTransportPolicy::kNone:
+      rtcConfig.setIceTransportPolicy("none");
+      break;
+    case blink::WebRTCIceTransportPolicy::kRelay:
+      rtcConfig.setIceTransportPolicy("relay");
+      break;
+    case blink::WebRTCIceTransportPolicy::kAll:
+      rtcConfig.setIceTransportPolicy("all");
+      break;
+  }
+
+  switch (blinkConfig.bundlePolicy) {
+    case blink::WebRTCBundlePolicy::kBalanced:
+      rtcConfig.setBundlePolicy("balanced");
+      break;
+    case blink::WebRTCBundlePolicy::kMaxBundle:
+      rtcConfig.setBundlePolicy("max-bundle");
+      break;
+    case blink::WebRTCBundlePolicy::kMaxCompat:
+      rtcConfig.setBundlePolicy("max-compat");
+      break;
+  }
+
+  switch (blinkConfig.rtcpMuxPolicy) {
+    case blink::WebRTCRtcpMuxPolicy::kNegotiate:
+      rtcConfig.setRtcpMuxPolicy("negotiate");
+      break;
+    case blink::WebRTCRtcpMuxPolicy::kRequire:
+      rtcConfig.setRtcpMuxPolicy("require");
+      break;
+  }
+
+  HeapVector<RTCIceServer> servers;
+  for (const WebRTCIceServer& blink_server : blinkConfig.iceServers) {
+    RTCIceServer server;
+    Vector<String> urlStrings;
+    StringOrStringSequence urls;
+    for (const WebURL& blink_url : blink_server.urls) {
+      String urlString(blink_url.string().utf8().c_str());

[dcheng, 2017/03/10 19:54:00]

Nit: omit utf8().c_str(), otherwise this turns a relatively cheap Blink string
copy (which is just a refcount bump) into copying and creating a new string.

In fact, the local here isn't necessary, and you can just wite
  urlStrings.push_back(blink_url.string());

[zhihuang1, 2017/03/11 00:40:33]

Oh I see.

+      urlStrings.push_back(urlString);
+    }
+    urls.setStringSequence(urlStrings);
+    server.setURLs(urls);
+    String username(blink_server.username.utf8().c_str());

[dcheng, 2017/03/10 19:54:00]

Same here and below: no local, and just pass the WebString to setUsername
directly (there's a conversion operator)

[zhihuang1, 2017/03/11 00:40:33]

Done.

+    server.setUsername(blink_server.username);
+    String credential(blink_server.credential.utf8().c_str());
+    server.setCredential(credential);
+    servers.push_back(server);
+  }
+  rtcConfig.setIceServers(servers);
+
+  HeapVector<Member<RTCCertificate>> certificates;
+  for (auto& blink_certificate : blinkConfig.certificates) {
+    certificates.push_back(new RTCCertificate(std::move(blink_certificate)));
+  }
+  rtcConfig.setCertificates(certificates);
+}
+
 void RTCPeerConnection::setConfiguration(
     ScriptState* scriptState,
     const RTCConfiguration& rtcConfiguration,