Replace SetCapturer and SetCaptureDevice by SetSource.

webrtc/api/objc/RTCAVFoundationVideoSource.mm

Index: webrtc/api/objc/RTCAVFoundationVideoSource.mm
diff --git a/webrtc/api/objc/RTCAVFoundationVideoSource.mm b/webrtc/api/objc/RTCAVFoundationVideoSource.mm
index 1005c7dfa122c6528adc6b46cfb14644c430fc5f..919190a4b9b321cfc28b8100a9cdc7174bd4e22d 100644
--- a/webrtc/api/objc/RTCAVFoundationVideoSource.mm
+++ b/webrtc/api/objc/RTCAVFoundationVideoSource.mm
@@ -19,11 +19,15 @@
 - (instancetype)initWithFactory:(RTCPeerConnectionFactory *)factory
                     constraints:(RTCMediaConstraints *)constraints {
   NSParameterAssert(factory);
-  rtc::scoped_ptr<webrtc::AVFoundationVideoCapturer> capturer;
-  capturer.reset(new webrtc::AVFoundationVideoCapturer());
+  webrtc::AVFoundationVideoCapturer *capturer =
+      new webrtc::AVFoundationVideoCapturer();
   rtc::scoped_refptr<webrtc::VideoTrackSourceInterface> source =
       factory.nativeFactory->CreateVideoSource(
-          capturer.release(), constraints.nativeConstraints.get());
+          capturer, constraints.nativeConstraints.get());
+  // We pass ownership of the capturer to the source, but since we own
+  // the source, it should be ok to keep a raw pointer to the
+  // capturer.
+  _capturer = static_cast<void*>(capturer);
   return [super initWithNativeVideoSource:source];
 }
 
@@ -44,12 +48,7 @@
 }
 
 - (webrtc::AVFoundationVideoCapturer *)capturer {
-  cricket::VideoCapturer *capturer = self.nativeVideoSource->GetVideoCapturer();
-  // This should be safe because no one should have changed the underlying video
-  // source.
-  webrtc::AVFoundationVideoCapturer *foundationCapturer =
-      static_cast<webrtc::AVFoundationVideoCapturer *>(capturer);
-  return foundationCapturer;
+  return static_cast<webrtc::AVFoundationVideoCapturer *>(_capturer);
 }
 
 @end