AppRTCMobile iOS: Use video encoder factory to manage codec preference.

List codecs from factory in settings, select by changing order in factory.

Bug: webrtc:7925
Change-Id: If3c45e56713104c88705c67560325d002e6d6700
Reviewed-on: https://webrtc-review.googlesource.com/3720
Commit-Queue: Anders Carlsson <andersc@webrtc.org>
Reviewed-by: Magnus Jedvert <magjed@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20312}
diff --git a/sdk/objc/Framework/Headers/WebRTC/RTCVideoCodec.h b/sdk/objc/Framework/Headers/WebRTC/RTCVideoCodec.h
index ad56a5d..bfd768a 100644
--- a/sdk/objc/Framework/Headers/WebRTC/RTCVideoCodec.h
+++ b/sdk/objc/Framework/Headers/WebRTC/RTCVideoCodec.h
@@ -84,7 +84,7 @@
 
 /** Holds information to identify a codec. Corresponds to cricket::VideoCodec. */
 RTC_EXPORT
-@interface RTCVideoCodecInfo : NSObject
+@interface RTCVideoCodecInfo : NSObject <NSCoding>
 
 - (instancetype)init NS_UNAVAILABLE;