ObjC SDK: Stop using built-in SW video codecs

This CL removes the use of default built-in SW in the ObjC layer. If a
client want to depend on the video SW codecs, they must inject them
explicitly.

Bug: webrtc:7925
Change-Id: If752e7f02109ff768dc5ec38d935203de85987c2
Reviewed-on: https://webrtc-review.googlesource.com/69800
Commit-Queue: Magnus Jedvert <magjed@webrtc.org>
Reviewed-by: Anders Carlsson <andersc@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23073}
diff --git a/sdk/objc/Framework/Headers/WebRTC/RTCVideoCodec.h b/sdk/objc/Framework/Headers/WebRTC/RTCVideoCodec.h
index c179b92..063963d 100644
--- a/sdk/objc/Framework/Headers/WebRTC/RTCVideoCodec.h
+++ b/sdk/objc/Framework/Headers/WebRTC/RTCVideoCodec.h
@@ -90,7 +90,7 @@
   RTCVideoCodecModeScreensharing,
 };
 
-/** Holds information to identify a codec. Corresponds to cricket::VideoCodec. */
+/** Holds information to identify a codec. Corresponds to webrtc::SdpVideoFormat. */
 RTC_EXPORT
 @interface RTCVideoCodecInfo : NSObject <NSCoding>