This CL adds RTCMTLVideoView.h and RTCCameraVideoCapturer.h to WebRTC.h
in order to fix a build issue that comes up when using WebRTC.framework from swift code.

BUG=webrtc:7488

Review-Url: https://codereview.webrtc.org/2832803002
Cr-Commit-Position: refs/heads/master@{#17909}
diff --git a/AUTHORS b/AUTHORS
index 6527da8..c11e96d 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -49,6 +49,7 @@
 Vladimir Beloborodov <VladimirTechMan@gmail.com>
 Vicken Simonian <vsimon@gmail.com>
 Victor Costan <costan@gmail.com>
+Xiaohong Xu <freemine@yeah.net>
 
 &yet LLC <*@andyet.com>
 Agora IO <*@agora.io>