Move RTCVideoSource to webrtc/api/objc.

webrtc/api/objc/RTCMediaSource+Private.h

-/*
- *  Copyright 2015 The WebRTC project authors. All Rights Reserved.
- *
- *  Use of this source code is governed by a BSD-style license
- *  that can be found in the LICENSE file in the root of the source
- *  tree. An additional intellectual property rights grant can be found
- *  in the file PATENTS.  All contributing project authors may
- *  be found in the AUTHORS file in the root of the source tree.
- */
-
-#import "RTCMediaSource.h"
-
-#include "talk/app/webrtc/mediastreaminterface.h"
-
-NS_ASSUME_NONNULL_BEGIN
-
-@interface RTCMediaSource ()
-
-/**
- * The MediaSourceInterface object passed to this RTCMediaSource during
- * construction.
- */
-@property(nonatomic, readonly)
-    rtc::scoped_refptr<webrtc::MediaSourceInterface> nativeMediaSource;
-
-/** Initialize an RTCMediaSource from a native MediaSourceInterface. */
-- (instancetype)initWithNativeMediaSource:
-    (rtc::scoped_refptr<webrtc::MediaSourceInterface>)nativeMediaSource
-    NS_DESIGNATED_INITIALIZER;
-
-+ (webrtc::MediaSourceInterface::SourceState)nativeSourceStateForState:
-    (RTCSourceState)state;
-
-+ (RTCSourceState)sourceStateForNativeState:
-    (webrtc::MediaSourceInterface::SourceState)nativeState;
-
-+ (NSString *)stringForState:(RTCSourceState)state;
-
-@end
-
-NS_ASSUME_NONNULL_END