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 626e5c91eb70f8eac21a3230002662126aa386f1..5b4f4cfd1952477c1988342e9d5395fcf4bba16b 100644
--- a/content/renderer/media/rtc_peer_connection_handler.cc
+++ b/content/renderer/media/rtc_peer_connection_handler.cc
@@ -185,18 +185,32 @@ void GetSdpAndTypeFromSessionDescription(
 void GetNativeRtcConfiguration(
     const blink::WebRTCConfiguration& blink_config,
     webrtc::PeerConnectionInterface::RTCConfiguration* webrtc_config) {
-  if (blink_config.isNull() || !webrtc_config)
+  if (!webrtc_config)

[tommi (sloooow) - chröme, 2015/09/16 18:13:40]

Is this even possible? maybe we should just replace this with a DCHECK.

[guoweis_left_chromium, 2015/09/16 18:51:03]

Done.

     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);
+
+  // 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;

[tommi (sloooow) - chröme, 2015/09/16 18:13:40]

this line, line 201 and the scope starting in 203 seem to be assuming that the
value of enable_localhost_ice_candidate will always be false.  If that's the
case, can you add a DCHECK at the top of this function?  If it's not the case,
then do we need to set this to false in 203?

[guoweis_left_chromium, 2015/09/16 18:51:03]

Yes, it was initialized to be false in the ctor of
webrtc::PeerConnectionInterface::RTCConfiguration. But adding explicit setting
to false is better.

+    return;
+  }
+
+  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()) {