Delete RTCAVFoundationVideoSource and related classes.

Bug: webrtc:8852
Change-Id: Ie073fe3f7bafc3d22fafef51f659e340d5a9250f
Reviewed-on: https://webrtc-review.googlesource.com/48620
Reviewed-by: Patrik Höglund <phoglund@webrtc.org>
Reviewed-by: Anders Carlsson <andersc@webrtc.org>
Commit-Queue: Kári Helgason <kthelgason@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21985}

sdk/objc/Framework/Classes/PeerConnection/RTCPeerConnectionFactory.mm

@@ -13,7 +13,6 @@
 #import "RTCPeerConnectionFactoryOptions+Private.h"
 
 #import "NSString+StdString.h"
-#import "RTCAVFoundationVideoSource+Private.h"
 #import "RTCAudioSource+Private.h"
 #import "RTCAudioTrack+Private.h"
 #import "RTCMediaConstraints+Private.h"
@@ -232,15 +231,6 @@
                                         trackId:trackId];
 }
 
-- (RTCAVFoundationVideoSource *)avFoundationVideoSourceWithConstraints:
-    (nullable RTCMediaConstraints *)constraints {
-#ifdef HAVE_NO_MEDIA
-  return nil;
-#else
-  return [[RTCAVFoundationVideoSource alloc] initWithFactory:self constraints:constraints];
-#endif
-}
-
 - (RTCVideoSource *)videoSource {
   rtc::scoped_refptr<webrtc::ObjcVideoTrackSource> objcVideoTrackSource(
       new rtc::RefCountedObject<webrtc::ObjcVideoTrackSource>());