Accept SDP with TRANSPORT attributes missing from bundled m= sections.

webrtc/p2p/base/transportdescriptionfactory.h

Index: webrtc/p2p/base/transportdescriptionfactory.h
diff --git a/webrtc/p2p/base/transportdescriptionfactory.h b/webrtc/p2p/base/transportdescriptionfactory.h
index 2dde5b12584b729f6a59963dedd76a82058fc942..ac04f048c610f7051710bb566f0ab263a1513ba7 100644
--- a/webrtc/p2p/base/transportdescriptionfactory.h
+++ b/webrtc/p2p/base/transportdescriptionfactory.h
@@ -53,9 +53,16 @@ class TransportDescriptionFactory {
   TransportDescription* CreateOffer(const TransportOptions& options,
       const TransportDescription* current_description) const;
   // Create a transport description that is a response to an offer.
+  //
+  // If |require_transport_attributes| is true, then TRANSPORT category
+  // attributes are expected to be present in |offer|, as defined by
+  // sdp-mux-attributes, and null will be returned otherwise. It's expected
+  // that this will be set to false for an m= section that's in a BUNDLE group
+  // but isn't the first m= section in the group.
   TransportDescription* CreateAnswer(
       const TransportDescription* offer,
       const TransportOptions& options,
+      bool require_transport_attributes,
       const TransportDescription* current_description) const;
 
  private: