Pass around the candidate removals events in IOS clients

webrtc/examples/objc/AppRTCDemo/RTCICECandidate+JSON.m

 /*
  *  Copyright 2014 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 31 matching lines @@
       [NSJSONSerialization dataWithJSONObject:json
                                       options:NSJSONWritingPrettyPrinted
                                         error:&error];
   if (error) {
     RTCLogError(@"Error serializing JSON: %@", error);
     return nil;
   }
   return data;
 }
 
+- (NSDictionary *)JSONDictionary{
+  NSDictionary *json = @{
+    kRTCICECandidateMLineIndexKey : @(self.sdpMLineIndex),
+    kRTCICECandidateMidKey : self.sdpMid,
+    kRTCICECandidateSdpKey : self.sdp
+  };
+  return json;
+}
+
 @end