Renamed VideoSourceInterface to VideoTrackSourceInterface.

Moved VideoSourceInterface to MediaStreamInterface.h
Renamed VideoSourceTest to VideoCapturerTrackSourceTest
Renamed VideoSource to VideoCaptureTrackSource and cl lint and cl format.
BUG=webrtc:5426
TBR=pthatcher@webrtc.org

Review URL: https://codereview.webrtc.org/1770003002 .

Cr-Commit-Position: refs/heads/master@{#11893}
diff --git a/webrtc/api/objc/RTCVideoSource+Private.h b/webrtc/api/objc/RTCVideoSource+Private.h
index c363d33..be064bd 100644
--- a/webrtc/api/objc/RTCVideoSource+Private.h
+++ b/webrtc/api/objc/RTCVideoSource+Private.h
@@ -17,15 +17,16 @@
 @interface RTCVideoSource ()
 
 /**
- * The VideoSourceInterface object passed to this RTCVideoSource during
+ * The VideoTrackSourceInterface object passed to this RTCVideoSource during
  * construction.
  */
 @property(nonatomic, readonly)
-    rtc::scoped_refptr<webrtc::VideoSourceInterface> nativeVideoSource;
+    rtc::scoped_refptr<webrtc::VideoTrackSourceInterface>
+        nativeVideoSource;
 
-/** Initialize an RTCVideoSource from a native VideoSourceInterface. */
+/** Initialize an RTCVideoSource from a native VideoTrackSourceInterface. */
 - (instancetype)initWithNativeVideoSource:
-    (rtc::scoped_refptr<webrtc::VideoSourceInterface>)nativeVideoSource
+    (rtc::scoped_refptr<webrtc::VideoTrackSourceInterface>)nativeVideoSource
     NS_DESIGNATED_INITIALIZER;
 
 + (webrtc::MediaSourceInterface::SourceState)nativeSourceStateForState: