Add media constraint-key constants for generating offers and answers

webrtc/sdk/objc/Framework/Classes/PeerConnection/RTCMediaConstraints.mm

 /*
  *  Copyright 2015 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 17 matching lines @@
     @(webrtc::MediaConstraintsInterface::kMaxHeight);
 NSString * const kRTCMediaConstraintsMinFrameRate =
     @(webrtc::MediaConstraintsInterface::kMinFrameRate);
 NSString * const kRTCMediaConstraintsMaxFrameRate =
     @(webrtc::MediaConstraintsInterface::kMaxFrameRate);
 NSString * const kRTCMediaConstraintsLevelControl =
     @(webrtc::MediaConstraintsInterface::kLevelControl);
 NSString * const kRTCMediaConstraintsAudioNetworkAdaptorConfig =
     @(webrtc::MediaConstraintsInterface::kAudioNetworkAdaptorConfig);
 
+NSString * const kRTCMediaConstraintsIceRestart =
+    @(webrtc::MediaConstraintsInterface::kIceRestart);
+NSString * const kRTCMediaConstraintsOfferToReceiveAudio =
+    @(webrtc::MediaConstraintsInterface::kOfferToReceiveAudio);
+NSString * const kRTCMediaConstraintsOfferToReceiveVideo =
+    @(webrtc::MediaConstraintsInterface::kOfferToReceiveVideo);
+NSString * const kRTCMediaConstraintsVoiceActivityDetection =
+    @(webrtc::MediaConstraintsInterface::kVoiceActivityDetection);
+
 NSString * const kRTCMediaConstraintsValueTrue =
     @(webrtc::MediaConstraintsInterface::kValueTrue);
 NSString * const kRTCMediaConstraintsValueFalse =
     @(webrtc::MediaConstraintsInterface::kValueFalse);
 
 namespace webrtc {
 
 MediaConstraints::~MediaConstraints() {}
 
 MediaConstraints::MediaConstraints() {}
@@ skipping 72 matching lines @@
           key.stdString, configValue));
     } else {
       nativeConstraints.push_back(webrtc::MediaConstraintsInterface::Constraint(
           key.stdString, value.stdString));
     }
   }
   return nativeConstraints;
 }
 
 @end