Replace SetCapturer and SetCaptureDevice by SetSource.

webrtc/api/objc/RTCAVFoundationVideoSource.h

Index: webrtc/api/objc/RTCAVFoundationVideoSource.h
diff --git a/webrtc/api/objc/RTCAVFoundationVideoSource.h b/webrtc/api/objc/RTCAVFoundationVideoSource.h
index 6d224d3f8e554067f50999007f876f0754c3e349..5b15e08ba0b8baa46a5f1af196348630af95bfb3 100644
--- a/webrtc/api/objc/RTCAVFoundationVideoSource.h
+++ b/webrtc/api/objc/RTCAVFoundationVideoSource.h
@@ -23,7 +23,13 @@ NS_ASSUME_NONNULL_BEGIN
  * guarantee its lifetime. Instead, we expose its properties through the ref
  * counted video source interface.
  */
-@interface RTCAVFoundationVideoSource : RTCVideoSource
+@interface RTCAVFoundationVideoSource : RTCVideoSource {
+  // TODO(nisse): This is a crude hack, the pointer really is a
+  // webrtc::AVFoundationVideoCapturer*, but using a proper
+  // declaration with namespaces breaks inclusion from .m files, i.e.
+  // files which are Objective-C but not Objective-C++.
+  void *_capturer;
+}
 
 - (instancetype)init NS_UNAVAILABLE;