Add signaling to support ICE renomination.

webrtc/p2p/base/transport.h

 /*
  *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 194 matching lines @@
 
   // The time period in which we will not switch the selected connection
   // when a new connection becomes receiving but the selected connection is not
   // in case that the selected connection may become receiving soon.
   rtc::Optional<int> receiving_switching_delay;
 
   // TODO(honghaiz): Change the default to regular nomination.
   // Default nomination mode if the remote does not support renomination.
   NominationMode default_nomination_mode = NominationMode::SEMI_AGGRESSIVE;
 
+  // If set to true, if the remote side supports ICE renomination, we will use
+  // renomination (if this side has the controlling role).
+  bool use_renomination_if_remote_supports = false;

[Taylor Brandstetter, 2016/08/08 22:28:16]

Why not just use `SetIceParameters` with `renomination` set to true for this
functionality? In fact, that's really what we *should* do, because if you SDP
munge to remove the "renomination" ICE option from the local description, we
shouldn't use renomination.

[honghaiz3, 2016/08/11 04:57:57]

So we will have a single control to control both 
1. Whether we support ICE renomination. 
2. Whether we will use ICE renomination if the remote supports. 
It makes sense to me. We don't need two control knobs for them. 

+
   IceConfig() {}
   IceConfig(int receiving_timeout_ms,
             int backup_connection_ping_interval,
             ContinualGatheringPolicy gathering_policy,
             bool prioritize_most_likely_candidate_pairs,
             int stable_writable_connection_ping_interval_ms,
             bool presume_writable_when_fully_relayed,
             int regather_on_failed_networks_interval_ms,
             int receiving_switching_delay_ms)
       : receiving_timeout(receiving_timeout_ms),
@@ skipping 189 matching lines @@
 
   ChannelMap channels_;
 
   RTC_DISALLOW_COPY_AND_ASSIGN(Transport);
 };
 
 
 }  // namespace cricket
 
 #endif  // WEBRTC_P2P_BASE_TRANSPORT_H_