Let CreateVideoDecoder take a cricket::VideoCodec.

webrtc/sdk/objc/Framework/Classes/VideoToolbox/objc_video_decoder_factory.mm

 /*
  *  Copyright 2017 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 85 matching lines @@
 
 ObjCVideoDecoderFactory::ObjCVideoDecoderFactory(id<RTCVideoDecoderFactory> decoder_factory)
     : decoder_factory_(decoder_factory) {}
 
 ObjCVideoDecoderFactory::~ObjCVideoDecoderFactory() {}
 
 id<RTCVideoDecoderFactory> ObjCVideoDecoderFactory::wrapped_decoder_factory() const {
   return decoder_factory_;
 }
 
-VideoDecoder *ObjCVideoDecoderFactory::CreateVideoDecoder(VideoCodecType type) {
-  const char *codec_name = CodecTypeToPayloadName(type);
-
-  NSString *codecName = [NSString stringWithUTF8String:codec_name];
+VideoDecoder *ObjCVideoDecoderFactory::CreateVideoDecoder(const cricket::VideoCodec &codec) {
+  NSString *codecName = [NSString stringWithUTF8String:codec.name.c_str()];

[magjed_webrtc, 2017/08/24 08:59:39]

I think we could simplify this whole function now by just doing:
id<RTCVideoDecoder> decoder = [decoder_factory_ createDecoder:[RTCVideoCodecInfo
initWithNativeVideoCodec:codec]];
return decoder ? new ObjCVideoDecoder(decoder) : nullptr;

[kthelgason, 2017/08/24 10:49:47]

Sure, we can do that, but that just moves the responsibility of making sure that
the codec being asked for is supported by the decoder.
I'd prefer to keep it like this for now, and if we decide to change it I think
it's a separate change.

[magjed_webrtc, 2017/08/25 15:55:01]

I think we should fix the C++ code in core WebRTC so that we don't try to create
invalid decoders in the first place, but let's fix it in a separate change as
you suggest.

   for (RTCVideoCodecInfo *codecInfo in decoder_factory_.supportedCodecs) {
     if ([codecName isEqualToString:codecInfo.name]) {
       id<RTCVideoDecoder> decoder = [decoder_factory_ createDecoder:codecInfo];
       return new ObjCVideoDecoder(decoder);
     }
   }
 
   return nullptr;
 }
 
 void ObjCVideoDecoderFactory::DestroyVideoDecoder(VideoDecoder *decoder) {
   delete decoder;
   decoder = nullptr;
 }
 
 }  // namespace webrtc