Enable generation of local host candidate when RTCConfiguration is null.

content/renderer/media/rtc_peer_connection_handler.cc

Index: content/renderer/media/rtc_peer_connection_handler.cc
diff --git a/content/renderer/media/rtc_peer_connection_handler.cc b/content/renderer/media/rtc_peer_connection_handler.cc
index 06953b591538f555283f61c717b6146b75ee14f5..181838af564e9d0086921219e6c6eebed4a4e011 100644
--- a/content/renderer/media/rtc_peer_connection_handler.cc
+++ b/content/renderer/media/rtc_peer_connection_handler.cc
@@ -185,18 +185,31 @@ void GetSdpAndTypeFromSessionDescription(
 void GetNativeRtcConfiguration(
     const blink::WebRTCConfiguration& blink_config,
     webrtc::PeerConnectionInterface::RTCConfiguration* webrtc_config) {
-  if (blink_config.isNull() || !webrtc_config)
+  DCHECK_EQ(webrtc_config->enable_localhost_ice_candidate, false);
+
+  // When we don't have WebRTCConfiguration, treat it as a special case where we
+  // should generate local host candidate. This will only be honored if
+  // enable_multiple_routes is disabled.
+  if (blink_config.isNull()) {
+    webrtc_config->enable_localhost_ice_candidate = true;
     return;
-  for (size_t i = 0; i < blink_config.numberOfServers(); ++i) {
-    webrtc::PeerConnectionInterface::IceServer server;
-    const blink::WebRTCICEServer& webkit_server =
-        blink_config.server(i);
-    server.username =
-        base::UTF16ToUTF8(base::StringPiece16(webkit_server.username()));
-    server.password =
-        base::UTF16ToUTF8(base::StringPiece16(webkit_server.credential()));
-    server.uri = webkit_server.uri().spec();
-    webrtc_config->servers.push_back(server);
+  }
+
+  if (blink_config.iceServers().isNull()) {
+    // Same as when iceServers is undefined or unspecified.
+    webrtc_config->enable_localhost_ice_candidate = true;
+  } else {
+    for (size_t i = 0; i < blink_config.iceServers().numberOfServers(); ++i) {
+      webrtc::PeerConnectionInterface::IceServer server;
+      const blink::WebRTCICEServer& webkit_server =
+          blink_config.iceServers().server(i);
+      server.username =
+          base::UTF16ToUTF8(base::StringPiece16(webkit_server.username()));
+      server.password =
+          base::UTF16ToUTF8(base::StringPiece16(webkit_server.credential()));
+      server.uri = webkit_server.uri().spec();
+      webrtc_config->servers.push_back(server);
+    }
   }
 
   switch (blink_config.iceTransports()) {