Tweaks for new Objective-C API.

webrtc/api/objc/RTCDataChannel.mm

Index: webrtc/api/objc/RTCDataChannel.mm
diff --git a/webrtc/api/objc/RTCDataChannel.mm b/webrtc/api/objc/RTCDataChannel.mm
index a1f484a1a29f60042170ce26b951c5bdc22cff74..5778cb5b7afd19602c754c6467268cbd0c6c06a2 100644
--- a/webrtc/api/objc/RTCDataChannel.mm
+++ b/webrtc/api/objc/RTCDataChannel.mm
@@ -123,7 +123,7 @@ class DataChannelDelegateAdapter : public DataChannelObserver {
   return _nativDataChannel->negotiated();
 }
 
-- (int)id {
+- (int)channelId {
   return _nativDataChannel->id();
 }
 
@@ -161,7 +161,7 @@ class DataChannelDelegateAdapter : public DataChannelObserver {
 
 - (NSString *)description {
   return [NSString stringWithFormat:@"RTCDataChannel:\n%ld\n%@\n%@",
-                                    (long)self.id,
+                                    (long)self.channelId,
                                     self.label,
                                     [[self class]
                                         stringForState:self.readyState]];