Delete deprecated and transitional stuff related to video frame refactoring.

webrtc/sdk/objc/Framework/Classes/objcvideotracksource.mm

Index: webrtc/sdk/objc/Framework/Classes/objcvideotracksource.mm
diff --git a/webrtc/sdk/objc/Framework/Classes/objcvideotracksource.mm b/webrtc/sdk/objc/Framework/Classes/objcvideotracksource.mm
index 942171be29b52c18ea957798c2d0d6447f5e695b..8394d664fbd9fba33420f4ba1de8fcd56bd0b9d1 100644
--- a/webrtc/sdk/objc/Framework/Classes/objcvideotracksource.mm
+++ b/webrtc/sdk/objc/Framework/Classes/objcvideotracksource.mm
@@ -12,6 +12,7 @@
 
 #import "RTCVideoFrame+Private.h"
 
+#include "webrtc/api/video/i420_buffer.h"
 #include "webrtc/common_video/include/corevideo_frame_buffer.h"
 
 namespace webrtc {
@@ -60,7 +61,7 @@ void ObjcVideoTrackSource::OnCapturedFrame(RTCVideoFrame* frame) {
   // not critical here.
   webrtc::VideoRotation rotation = static_cast<webrtc::VideoRotation>(frame.rotation);
   if (apply_rotation() && rotation != kVideoRotation_0) {
-    buffer = I420Buffer::Rotate(buffer->NativeToI420Buffer(), rotation);
+    buffer = I420Buffer::Rotate(*buffer->NativeToI420Buffer(), rotation);
     rotation = kVideoRotation_0;
   }