Fixed a crash in Objective-C clients when data channel becomes closed.

webrtc/sdk/objc/Framework/Classes/RTCDataChannel.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 77 matching lines @@
   rtc::scoped_refptr<webrtc::DataChannelInterface> _nativeDataChannel;
   std::unique_ptr<webrtc::DataChannelDelegateAdapter> _observer;
   BOOL _isObserverRegistered;
 }
 
 @synthesize delegate = _delegate;
 
 - (void)dealloc {
   // Handles unregistering the observer properly. We need to do this because
   // there may still be other references to the underlying data channel.
-  self.delegate = nil;
+  _nativeDataChannel->UnregisterObserver();
 }
 
 - (NSString *)label {
   return [NSString stringForStdString:_nativeDataChannel->label()];
 }
 
 - (BOOL)isReliable {
   return _nativeDataChannel->reliable();
 }
 
@@ skipping 31 matching lines @@
 
 - (RTCDataChannelState)readyState {
   return [[self class] dataChannelStateForNativeState:
       _nativeDataChannel->state()];
 }
 
 - (uint64_t)bufferedAmount {
   return _nativeDataChannel->buffered_amount();
 }
 
-- (void)setDelegate:(id<RTCDataChannelDelegate>)delegate {
-  if (_delegate == delegate) {
-    return;
-  }
-  if (_isObserverRegistered) {
-    _nativeDataChannel->UnregisterObserver();
-    _isObserverRegistered = NO;
-  }
-  _delegate = delegate;
-  if (_delegate) {
-    _nativeDataChannel->RegisterObserver(_observer.get());
-    _isObserverRegistered = YES;
-  }
-}
-
 - (void)close {
   _nativeDataChannel->Close();
 }
 
 - (BOOL)sendData:(RTCDataBuffer *)data {
   return _nativeDataChannel->Send(*data.nativeDataBuffer);
 }
 
 - (NSString *)description {
   return [NSString stringWithFormat:@"RTCDataChannel:\n%ld\n%@\n%@",
                                     (long)self.channelId,
                                     self.label,
                                     [[self class]
                                         stringForState:self.readyState]];
 }
 
 #pragma mark - Private
 
 - (instancetype)initWithNativeDataChannel:
     (rtc::scoped_refptr<webrtc::DataChannelInterface>)nativeDataChannel {
   NSParameterAssert(nativeDataChannel);
   if (self = [super init]) {
     _nativeDataChannel = nativeDataChannel;
     _observer.reset(new webrtc::DataChannelDelegateAdapter(self));
+    _nativeDataChannel->RegisterObserver(_observer.get());
   }
   return self;
 }
 
 + (webrtc::DataChannelInterface::DataState)
     nativeDataChannelStateForState:(RTCDataChannelState)state {
   switch (state) {
     case RTCDataChannelStateConnecting:
       return webrtc::DataChannelInterface::DataState::kConnecting;
     case RTCDataChannelStateOpen:
@@ skipping 26 matching lines @@
     case RTCDataChannelStateOpen:
       return @"Open";
     case RTCDataChannelStateClosing:
       return @"Closing";
     case RTCDataChannelStateClosed:
       return @"Closed";
   }
 }
 
 @end