Reland of Injectable Obj-C video codecs

webrtc/sdk/objc/Framework/Headers/WebRTC/RTCPeerConnectionFactory.h

 /*
  *  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 <Foundation/Foundation.h>
 
 #import <WebRTC/RTCMacros.h>
 
 NS_ASSUME_NONNULL_BEGIN
 
 @class RTCAVFoundationVideoSource;
 @class RTCAudioSource;
 @class RTCAudioTrack;
 @class RTCConfiguration;
 @class RTCMediaConstraints;
 @class RTCMediaStream;
 @class RTCPeerConnection;
 @class RTCVideoSource;
 @class RTCVideoTrack;
 @protocol RTCPeerConnectionDelegate;
+@protocol RTCVideoEncoderFactory;
+@protocol RTCVideoDecoderFactory;
 
 RTC_EXPORT
 @interface RTCPeerConnectionFactory : NSObject
 
-- (instancetype)init NS_DESIGNATED_INITIALIZER;
+/* Initialize object with default H264 video encoder/decoder factories */
+- (instancetype)init;
+
+/* Initialize object with injectable video encoder/decoder factories */
+- (instancetype)initWithEncoderFactory:(nullable id<RTCVideoEncoderFactory>)encoderFactory
+                        decoderFactory:(nullable id<RTCVideoDecoderFactory>)decoderFactory
+    NS_DESIGNATED_INITIALIZER;
 
 /** Initialize an RTCAudioSource with constraints. */
 - (RTCAudioSource *)audioSourceWithConstraints:(nullable RTCMediaConstraints *)constraints;
 
 /** Initialize an RTCAudioTrack with an id. Convenience ctor to use an audio source with no
  *  constraints.
  */
 - (RTCAudioTrack *)audioTrackWithTrackId:(NSString *)trackId;
 
 /** Initialize an RTCAudioTrack with a source and an id. */
@@ skipping 29 matching lines @@
 /** Start an AecDump recording. This API call will likely change in the future. */
 - (BOOL)startAecDumpWithFilePath:(NSString *)filePath
                   maxSizeInBytes:(int64_t)maxSizeInBytes;
 
 /* Stop an active AecDump recording */
 - (void)stopAecDump;
 
 @end
 
 NS_ASSUME_NONNULL_END