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}

sdk/objc/Framework/Classes/PeerConnection/RTCDefaultVideoDecoderFactory.m

@@ -11,11 +11,9 @@
 #import "WebRTC/RTCVideoCodecFactory.h"
 
 #import "WebRTC/RTCVideoCodecH264.h"
-#if defined(USE_BUILTIN_SW_CODECS)
-#import "WebRTC/RTCVideoDecoderVP8.h"  // nogncheck
+#import "WebRTC/RTCVideoDecoderVP8.h"
 #if !defined(RTC_DISABLE_VP9)
-#import "WebRTC/RTCVideoDecoderVP9.h"  // nogncheck
-#endif
+#import "WebRTC/RTCVideoDecoderVP9.h"
 #endif
 
 @implementation RTCDefaultVideoDecoderFactory
@@ -23,13 +21,11 @@
 - (id<RTCVideoDecoder>)createDecoder:(RTCVideoCodecInfo *)info {
   if ([info.name isEqualToString:kRTCVideoCodecH264Name]) {
     return [[RTCVideoDecoderH264 alloc] init];
-#if defined(USE_BUILTIN_SW_CODECS)
   } else if ([info.name isEqualToString:kRTCVideoCodecVp8Name]) {
     return [RTCVideoDecoderVP8 vp8Decoder];
 #if !defined(RTC_DISABLE_VP9)
   } else if ([info.name isEqualToString:kRTCVideoCodecVp9Name]) {
     return [RTCVideoDecoderVP9 vp9Decoder];
-#endif
 #endif
   }
 
@@ -39,11 +35,9 @@
 - (NSArray<RTCVideoCodecInfo *> *)supportedCodecs {
   return @[
     [[RTCVideoCodecInfo alloc] initWithName:kRTCVideoCodecH264Name],
-#if defined(USE_BUILTIN_SW_CODECS)
     [[RTCVideoCodecInfo alloc] initWithName:kRTCVideoCodecVp8Name],
 #if !defined(RTC_DISABLE_VP9)
     [[RTCVideoCodecInfo alloc] initWithName:kRTCVideoCodecVp9Name],
-#endif
 #endif
   ];
 }