Mark public ObjC APIs as explicitly visible.
BUG=
Review URL: https://codereview.webrtc.org/1899573002
Cr-Commit-Position: refs/heads/master@{#12431}
diff --git a/webrtc/api/objc/RTCMediaStream.h b/webrtc/api/objc/RTCMediaStream.h
index 50ae7df..d5de6d3 100644
--- a/webrtc/api/objc/RTCMediaStream.h
+++ b/webrtc/api/objc/RTCMediaStream.h
@@ -10,12 +10,15 @@
#import <Foundation/Foundation.h>
+#import "webrtc/base/objc/RTCMacros.h"
+
NS_ASSUME_NONNULL_BEGIN
@class RTCAudioTrack;
@class RTCPeerConnectionFactory;
@class RTCVideoTrack;
+RTC_EXPORT
@interface RTCMediaStream : NSObject
/** The audio tracks in this stream. */