Pass the sctp command-line flag to Libjingle as an internal-only constraint.

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 30707cac02a2f3df08cf80fd2f40687182daf9b8..98cb5c8b2494b4d2a9ccd8e83e5ea7ed6d0c3ca2 100644
--- a/content/renderer/media/rtc_peer_connection_handler.cc
+++ b/content/renderer/media/rtc_peer_connection_handler.cc
@@ -8,10 +8,12 @@
 #include <utility>
 #include <vector>
 
+#include "base/command_line.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/stl_util.h"
 #include "base/utf_string_conversions.h"
+#include "content/public/common/content_switches.h"
 #include "content/renderer/media/media_stream_dependency_factory.h"
 #include "content/renderer/media/peer_connection_tracker.h"
 #include "content/renderer/media/remote_media_stream_impl.h"
@@ -338,6 +340,9 @@ bool RTCPeerConnectionHandler::initialize(
     const WebKit::WebRTCConfiguration& server_configuration,
     const WebKit::WebMediaConstraints& options) {
   DCHECK(frame_);
+  static bool sctp_data_channel_enabled =

[tommi (sloooow) - chröme, 2013/05/21 08:03:24]

nit: no need to cache this in a static. initialize is rarely called and we
usually don't cache HasSwitch() results.

[jiayl, 2013/05/21 16:57:15]

Done.

+      CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kEnableSCTPDataChannels);
 
   peer_connection_tracker_ =
       RenderThreadImpl::current()->peer_connection_tracker();
@@ -346,6 +351,14 @@ bool RTCPeerConnectionHandler::initialize(
   GetNativeIceServers(server_configuration, &servers);
 
   RTCMediaConstraints constraints(options);
+
+  if (sctp_data_channel_enabled) {
+    // TODO(jiayl): replace the hard coded string with
+    // webrtc::MediaConstraintsInterface::kEnbaleSctpDataChannels when

[tommi (sloooow) - chröme, 2013/05/21 08:03:24]

s/kEnbale/kEnable

[jiayl, 2013/05/21 16:57:15]

Done.

+    // the Libjingle change is rolled.

[tommi (sloooow) - chröme, 2013/05/21 08:03:24]

when will the libjingle change be rolled?  Could we perhaps just roll it before
we land this cl?

[jiayl, 2013/05/21 16:57:15]

The libjingle CL adding these strings depends on another libjingle CL that is
not approved yet. They should be committed and rolled by end of this week. I
submitted this CL in parallel per discussion with Justin, in order to minimize
the delay and leave enough baking time so that we can remove the flag by M29
cut.
On 2013/05/21 08:03:24, tommi wrote:

+    constraints.AddOptional("internalSctpDataChannels", "true");
+  }
+
   native_peer_connection_ =
       dependency_factory_->CreatePeerConnection(
           servers, &constraints, frame_, this);