Add 16-bit network id to the candidate signaling.

webrtc/p2p/base/stun.h

Index: webrtc/p2p/base/stun.h
diff --git a/webrtc/p2p/base/stun.h b/webrtc/p2p/base/stun.h
index 9c8471304b48aeadce058f608ad34337acef57e7..a55b81c6f0c4e71e641802803afec61b3ee7acc1 100644
--- a/webrtc/p2p/base/stun.h
+++ b/webrtc/p2p/base/stun.h
@@ -606,7 +606,10 @@ enum IceAttributeType {
   STUN_ATTR_USE_CANDIDATE = 0x0025,    // No content, Length = 0
   STUN_ATTR_ICE_CONTROLLED = 0x8029,   // UInt64
   STUN_ATTR_ICE_CONTROLLING = 0x802A,  // UInt64
-  STUN_ATTR_NETWORK_COST = 0xC057      // UInt32
+  STUN_ATTR_NETWORK_COST = 0xC057,     // UInt32. Deprecated
+  // UInt32. The higher 16 bits are the network ID. The lower 16 bits are the
+  // network cost.
+  STUN_ATTR_NETWORK_INFO = 0xC058

[pthatcher1, 2016/03/21 17:49:24]

I think we could just rename 0xC057 to STUN_ATTR_NETWORK_INFO and not have to
change the attribute ID.  

[honghaiz3, 2016/03/22 16:30:03]

I am afraid of potential confusions between an old and a new client as I
explained in another response.

 };
 
 // RFC 5245-defined errors.
@@ -622,6 +625,7 @@ class IceMessage : public StunMessage {
     switch (type) {
       case STUN_ATTR_PRIORITY:
       case STUN_ATTR_NETWORK_COST:
+      case STUN_ATTR_NETWORK_INFO:
         return STUN_VALUE_UINT32;
       case STUN_ATTR_USE_CANDIDATE:   return STUN_VALUE_BYTE_STRING;
       case STUN_ATTR_ICE_CONTROLLED:  return STUN_VALUE_UINT64;