Update API for Objective-C RTCPeerConnection.

webrtc/api/objc/RTCPeerConnection+DataChannel.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.
+ */
+
+#import "webrtc/api/objc/RTCPeerConnection+Private.h"
+
+#import "webrtc/api/objc/RTCDataChannel+Private.h"
+#import "webrtc/api/objc/RTCDataChannelConfiguration+Private.h"
+#import "webrtc/base/objc/NSString+StdString.h"
+
+@implementation RTCPeerConnection (DataChannel)
+
+- (RTCDataChannel *)dataChannelForLabel:(NSString *)label
+                          configuration:
+    (RTCDataChannelConfiguration *)configuration {
+  std::string labelString = [NSString stdStringForString:label];
+  const webrtc::DataChannelInit nativeInit =
+      configuration.nativeDataChannelInit;
+  rtc::scoped_refptr<webrtc::DataChannelInterface> dataChannel =
+      self.nativePeerConnection->CreateDataChannel(labelString,
+                                                   &nativeInit);
+  return [[RTCDataChannel alloc] initWithNativeDataChannel:dataChannel];
+}
+
+@end