Move RTCAVFoundationCapturer to webrtc/api/objc.

webrtc/api/BUILD.gn

Index: webrtc/api/BUILD.gn
diff --git a/webrtc/api/BUILD.gn b/webrtc/api/BUILD.gn
index ec52046facebdb00e89f8227f4a010a121ffd5ef..c1e553a13aa5faa1feb9f171e893dc2003c7c9ec 100644
--- a/webrtc/api/BUILD.gn
+++ b/webrtc/api/BUILD.gn
@@ -18,6 +18,9 @@ if (is_ios) {
       "-Wobjc-missing-property-synthesis",
     ]
     sources = [
+      "objc/RTCAVFoundationVideoSource+Private.h",
+      "objc/RTCAVFoundationVideoSource.h",
+      "objc/RTCAVFoundationVideoSource.mm",
       "objc/RTCIceServer+Private.h",
       "objc/RTCIceServer.h",
       "objc/RTCIceServer.mm",
@@ -28,6 +31,8 @@ if (is_ios) {
       "objc/RTCVideoSource.h",
       "objc/RTCVideoSource.mm",
       "objc/WebRTC-Prefix.pch",
+      "objc/avfoundationvideocapturer.h",
+      "objc/avfoundationvideocapturer.mm",
     ]
   }
 }