Mark public ObjC APIs as explicitly visible.

webrtc/api/objc/RTCOpenGLVideoRenderer.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 <Foundation/Foundation.h>
 #if TARGET_OS_IPHONE
 #import <GLKit/GLKit.h>
 #else
 #import <AppKit/NSOpenGL.h>
 #endif
 
+#import "webrtc/base/objc/RTCMacros.h"
+
 NS_ASSUME_NONNULL_BEGIN
 
 @class RTCVideoFrame;
 
 // RTCOpenGLVideoRenderer issues appropriate OpenGL commands to draw a frame to
 // the currently bound framebuffer. Supports OpenGL 3.2 and OpenGLES 2.0. OpenGL
 // framebuffer creation and management should be handled elsewhere using the
 // same context used to initialize this class.
+RTC_EXPORT
 @interface RTCOpenGLVideoRenderer : NSObject
 
 // The last successfully drawn frame. Used to avoid drawing frames unnecessarily
 // hence saving battery life by reducing load.
 @property(nonatomic, readonly) RTCVideoFrame *lastDrawnFrame;
 
 #if TARGET_OS_IPHONE
 - (instancetype)initWithContext:(EAGLContext *)context
     NS_DESIGNATED_INITIALIZER;
 #else
@@ skipping 13 matching lines @@
 // Sets up the OpenGL state needed for rendering.
 - (void)setupGL;
 // Tears down the OpenGL state created by |setupGL|.
 - (void)teardownGL;
 
 - (instancetype)init NS_UNAVAILABLE;
 
 @end
 
 NS_ASSUME_NONNULL_END