Refactor some ObjC API init methods.

webrtc/api/objc/RTCVideoTrack.h

Index: webrtc/api/objc/RTCVideoTrack.h
diff --git a/webrtc/api/objc/RTCVideoTrack.h b/webrtc/api/objc/RTCVideoTrack.h
index e8dad3b9e1810d150bf7693ca1cec5499c2bfbfc..1d8837606811d74e448cea1d5082bd524673ce81 100644
--- a/webrtc/api/objc/RTCVideoTrack.h
+++ b/webrtc/api/objc/RTCVideoTrack.h
@@ -23,11 +23,6 @@ NS_ASSUME_NONNULL_BEGIN
 
 - (instancetype)init NS_UNAVAILABLE;
 
-/** Initialize an RTCVideoTrack with its source and an id. */
-- (instancetype)initWithFactory:(RTCPeerConnectionFactory *)factory
-                         source:(RTCVideoSource *)source
-                        trackId:(NSString *)trackId;
-
 /** Register a renderer that will render all frames received on this track. */
 - (void)addRenderer:(id<RTCVideoRenderer>)renderer;