Rename RTC_EXPORT to RTC_OBJC_EXPORT.

A new version of RTC_EXPORT will be introduced by [1] and it will be
used by WebRTC native code.

This CL renames the current RTC_EXPORT to RTC_OBJC_EXPORT in order
to avoid to mix them. It has been decided to avoid to unify them because
RTC_OBJC_EXPORT always marks symbols with default visibility, while
RTC_EXPORT will do it only when COMPONENT_BUILD is defined.

[1] - https://webrtc-review.googlesource.com/c/src/+/97960 is

Bug: webrtc:9419
Change-Id: I56a3fc6601c72d3ad6a58f9961a00e3761dfb5da
Reviewed-on: https://webrtc-review.googlesource.com/100521
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Reviewed-by: Anders Carlsson <andersc@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24754}
diff --git a/sdk/objc/components/audio/RTCAudioSession.h b/sdk/objc/components/audio/RTCAudioSession.h
index a8325b6..d43418b 100644
--- a/sdk/objc/components/audio/RTCAudioSession.h
+++ b/sdk/objc/components/audio/RTCAudioSession.h
@@ -27,7 +27,7 @@
 // Surfaces AVAudioSession events. WebRTC will listen directly for notifications
 // from AVAudioSession and handle them before calling these delegate methods,
 // at which point applications can perform additional processing if required.
-RTC_EXPORT
+RTC_OBJC_EXPORT
 @protocol RTCAudioSessionDelegate <NSObject>
 
 @optional
@@ -102,7 +102,7 @@
  *  activation state has changed outside of RTCAudioSession. The current known use
  *  case of this is when CallKit activates the audio session for the application
  */
-RTC_EXPORT
+RTC_OBJC_EXPORT
 @protocol RTCAudioSessionActivationDelegate <NSObject>
 
 /** Called when the audio session is activated outside of the app by iOS. */
@@ -120,7 +120,7 @@
  *  RTCAudioSession also coordinates activation so that the audio session is
  *  activated only once. See |setActive:error:|.
  */
-RTC_EXPORT
+RTC_OBJC_EXPORT
 @interface RTCAudioSession : NSObject <RTCAudioSessionActivationDelegate>
 
 /** Convenience property to access the AVAudioSession singleton. Callers should
diff --git a/sdk/objc/components/audio/RTCAudioSessionConfiguration.h b/sdk/objc/components/audio/RTCAudioSessionConfiguration.h
index 3eb5e3a..9f3765d 100644
--- a/sdk/objc/components/audio/RTCAudioSessionConfiguration.h
+++ b/sdk/objc/components/audio/RTCAudioSessionConfiguration.h
@@ -22,7 +22,7 @@
 RTC_EXTERN const double kRTCAudioSessionLowComplexityIOBufferDuration;
 
 // Struct to hold configuration values.
-RTC_EXPORT
+RTC_OBJC_EXPORT
 @interface RTCAudioSessionConfiguration : NSObject
 
 @property(nonatomic, strong) NSString *category;
diff --git a/sdk/objc/components/capturer/RTCCameraVideoCapturer.h b/sdk/objc/components/capturer/RTCCameraVideoCapturer.h
index 4333baf..2b5e56f 100644
--- a/sdk/objc/components/capturer/RTCCameraVideoCapturer.h
+++ b/sdk/objc/components/capturer/RTCCameraVideoCapturer.h
@@ -16,7 +16,7 @@
 
 NS_ASSUME_NONNULL_BEGIN
 
-RTC_EXPORT
+RTC_OBJC_EXPORT
 // Camera capture that implements RTCVideoCapturer. Delivers frames to a RTCVideoCapturerDelegate
 // (usually RTCVideoSource).
 NS_EXTENSION_UNAVAILABLE_IOS("Camera not available in app extensions.")
diff --git a/sdk/objc/components/capturer/RTCFileVideoCapturer.h b/sdk/objc/components/capturer/RTCFileVideoCapturer.h
index 60a9afa..0782588 100644
--- a/sdk/objc/components/capturer/RTCFileVideoCapturer.h
+++ b/sdk/objc/components/capturer/RTCFileVideoCapturer.h
@@ -24,7 +24,7 @@
  *
  * See @c RTCVideoCapturer for more info on capturers.
  */
-RTC_EXPORT
+RTC_OBJC_EXPORT
 
 NS_CLASS_AVAILABLE_IOS(10)
 @interface RTCFileVideoCapturer : RTCVideoCapturer
diff --git a/sdk/objc/components/renderer/metal/RTCMTLNSVideoView.h b/sdk/objc/components/renderer/metal/RTCMTLNSVideoView.h
index 891b377..ffed4b8 100644
--- a/sdk/objc/components/renderer/metal/RTCMTLNSVideoView.h
+++ b/sdk/objc/components/renderer/metal/RTCMTLNSVideoView.h
@@ -14,7 +14,7 @@
 
 NS_AVAILABLE_MAC(10.11)
 
-RTC_EXPORT
+RTC_OBJC_EXPORT
 @interface RTCMTLNSVideoView : NSView <RTCVideoRenderer>
 
 @property(nonatomic, weak) id<RTCVideoViewDelegate> delegate;
diff --git a/sdk/objc/components/renderer/metal/RTCMTLVideoView.h b/sdk/objc/components/renderer/metal/RTCMTLVideoView.h
index ff64ba3..36cb144 100644
--- a/sdk/objc/components/renderer/metal/RTCMTLVideoView.h
+++ b/sdk/objc/components/renderer/metal/RTCMTLVideoView.h
@@ -26,7 +26,7 @@
  */
 NS_CLASS_AVAILABLE_IOS(9)
 
-RTC_EXPORT
+RTC_OBJC_EXPORT
 @interface RTCMTLVideoView : UIView<RTCVideoRenderer>
 
 @property(nonatomic, weak) id<RTCVideoViewDelegate> delegate;
diff --git a/sdk/objc/components/renderer/opengl/RTCEAGLVideoView.h b/sdk/objc/components/renderer/opengl/RTCEAGLVideoView.h
index 50bbf2e..c35fc2d 100644
--- a/sdk/objc/components/renderer/opengl/RTCEAGLVideoView.h
+++ b/sdk/objc/components/renderer/opengl/RTCEAGLVideoView.h
@@ -19,7 +19,7 @@
 
 @class RTCEAGLVideoView;
 
-RTC_EXPORT
+RTC_OBJC_EXPORT
 @protocol RTCEAGLVideoViewDelegate <RTCVideoViewDelegate>
 @end
 
@@ -27,7 +27,7 @@
  * RTCEAGLVideoView is an RTCVideoRenderer which renders video frames in its
  * bounds using OpenGLES 2.0 or OpenGLES 3.0.
  */
-RTC_EXPORT
+RTC_OBJC_EXPORT
 NS_EXTENSION_UNAVAILABLE_IOS("Rendering not available in app extensions.")
 @interface RTCEAGLVideoView : UIView <RTCVideoRenderer>
 
diff --git a/sdk/objc/components/renderer/opengl/RTCNSGLVideoView.h b/sdk/objc/components/renderer/opengl/RTCNSGLVideoView.h
index ad47705..2540f38 100644
--- a/sdk/objc/components/renderer/opengl/RTCNSGLVideoView.h
+++ b/sdk/objc/components/renderer/opengl/RTCNSGLVideoView.h
@@ -21,11 +21,11 @@
 
 @class RTCNSGLVideoView;
 
-RTC_EXPORT
+RTC_OBJC_EXPORT
 @protocol RTCNSGLVideoViewDelegate <RTCVideoViewDelegate>
 @end
 
-RTC_EXPORT
+RTC_OBJC_EXPORT
 @interface RTCNSGLVideoView : NSOpenGLView <RTCVideoRenderer>
 
 @property(nonatomic, weak) id<RTCVideoViewDelegate> delegate;
diff --git a/sdk/objc/components/renderer/opengl/RTCVideoViewShading.h b/sdk/objc/components/renderer/opengl/RTCVideoViewShading.h
index a570129..6876cc3 100644
--- a/sdk/objc/components/renderer/opengl/RTCVideoViewShading.h
+++ b/sdk/objc/components/renderer/opengl/RTCVideoViewShading.h
@@ -18,7 +18,7 @@
  * RTCVideoViewShading provides a way for apps to customize the OpenGL(ES) shaders used in
  * rendering for the RTCEAGLVideoView/RTCNSGLVideoView.
  */
-RTC_EXPORT
+RTC_OBJC_EXPORT
 @protocol RTCVideoViewShading <NSObject>
 
 /** Callback for I420 frames. Each plane is given as a texture. */
diff --git a/sdk/objc/components/video_codec/RTCCodecSpecificInfoH264.h b/sdk/objc/components/video_codec/RTCCodecSpecificInfoH264.h
index e9af571..ece9570 100644
--- a/sdk/objc/components/video_codec/RTCCodecSpecificInfoH264.h
+++ b/sdk/objc/components/video_codec/RTCCodecSpecificInfoH264.h
@@ -19,7 +19,7 @@
   RTCH264PacketizationModeSingleNalUnit        // Mode 0 - only single NALU allowed
 };
 
-RTC_EXPORT
+RTC_OBJC_EXPORT
 @interface RTCCodecSpecificInfoH264 : NSObject <RTCCodecSpecificInfo>
 
 @property(nonatomic, assign) RTCH264PacketizationMode packetizationMode;
diff --git a/sdk/objc/components/video_codec/RTCDefaultVideoDecoderFactory.h b/sdk/objc/components/video_codec/RTCDefaultVideoDecoderFactory.h
index 1ad9c43..7ca9463 100644
--- a/sdk/objc/components/video_codec/RTCDefaultVideoDecoderFactory.h
+++ b/sdk/objc/components/video_codec/RTCDefaultVideoDecoderFactory.h
@@ -18,7 +18,7 @@
 /** This decoder factory include support for all codecs bundled with WebRTC. If using custom
  *  codecs, create custom implementations of RTCVideoEncoderFactory and RTCVideoDecoderFactory.
  */
-RTC_EXPORT
+RTC_OBJC_EXPORT
 @interface RTCDefaultVideoDecoderFactory : NSObject <RTCVideoDecoderFactory>
 @end
 
diff --git a/sdk/objc/components/video_codec/RTCDefaultVideoEncoderFactory.h b/sdk/objc/components/video_codec/RTCDefaultVideoEncoderFactory.h
index b0e0af6..c45e543 100644
--- a/sdk/objc/components/video_codec/RTCDefaultVideoEncoderFactory.h
+++ b/sdk/objc/components/video_codec/RTCDefaultVideoEncoderFactory.h
@@ -18,7 +18,7 @@
 /** This encoder factory include support for all codecs bundled with WebRTC. If using custom
  *  codecs, create custom implementations of RTCVideoEncoderFactory and RTCVideoDecoderFactory.
  */
-RTC_EXPORT
+RTC_OBJC_EXPORT
 @interface RTCDefaultVideoEncoderFactory : NSObject <RTCVideoEncoderFactory>
 
 @property(nonatomic, retain) RTCVideoCodecInfo *preferredCodec;
diff --git a/sdk/objc/components/video_codec/RTCH264ProfileLevelId.h b/sdk/objc/components/video_codec/RTCH264ProfileLevelId.h
index 7b4e788..56b3532 100644
--- a/sdk/objc/components/video_codec/RTCH264ProfileLevelId.h
+++ b/sdk/objc/components/video_codec/RTCH264ProfileLevelId.h
@@ -12,11 +12,11 @@
 
 #import "RTCMacros.h"
 
-RTC_EXPORT extern NSString *const kRTCVideoCodecH264Name;
-RTC_EXPORT extern NSString *const kRTCLevel31ConstrainedHigh;
-RTC_EXPORT extern NSString *const kRTCLevel31ConstrainedBaseline;
-RTC_EXPORT extern NSString *const kRTCMaxSupportedH264ProfileLevelConstrainedHigh;
-RTC_EXPORT extern NSString *const kRTCMaxSupportedH264ProfileLevelConstrainedBaseline;
+RTC_OBJC_EXPORT extern NSString *const kRTCVideoCodecH264Name;
+RTC_OBJC_EXPORT extern NSString *const kRTCLevel31ConstrainedHigh;
+RTC_OBJC_EXPORT extern NSString *const kRTCLevel31ConstrainedBaseline;
+RTC_OBJC_EXPORT extern NSString *const kRTCMaxSupportedH264ProfileLevelConstrainedHigh;
+RTC_OBJC_EXPORT extern NSString *const kRTCMaxSupportedH264ProfileLevelConstrainedBaseline;
 
 /** H264 Profiles and levels. */
 typedef NS_ENUM(NSUInteger, RTCH264Profile) {
@@ -47,7 +47,7 @@
   RTCH264Level5_2 = 52
 };
 
-RTC_EXPORT
+RTC_OBJC_EXPORT
 @interface RTCH264ProfileLevelId : NSObject
 
 @property(nonatomic, readonly) RTCH264Profile profile;
diff --git a/sdk/objc/components/video_codec/RTCVideoDecoderFactoryH264.h b/sdk/objc/components/video_codec/RTCVideoDecoderFactoryH264.h
index 850ba7e..4fcff1d 100644
--- a/sdk/objc/components/video_codec/RTCVideoDecoderFactoryH264.h
+++ b/sdk/objc/components/video_codec/RTCVideoDecoderFactoryH264.h
@@ -13,6 +13,6 @@
 #import "RTCMacros.h"
 #import "RTCVideoDecoderFactory.h"
 
-RTC_EXPORT
+RTC_OBJC_EXPORT
 @interface RTCVideoDecoderFactoryH264 : NSObject <RTCVideoDecoderFactory>
 @end
diff --git a/sdk/objc/components/video_codec/RTCVideoDecoderH264.h b/sdk/objc/components/video_codec/RTCVideoDecoderH264.h
index 227200f..b860276 100644
--- a/sdk/objc/components/video_codec/RTCVideoDecoderH264.h
+++ b/sdk/objc/components/video_codec/RTCVideoDecoderH264.h
@@ -13,6 +13,6 @@
 #import "RTCMacros.h"
 #import "RTCVideoDecoder.h"
 
-RTC_EXPORT
+RTC_OBJC_EXPORT
 @interface RTCVideoDecoderH264 : NSObject <RTCVideoDecoder>
 @end
diff --git a/sdk/objc/components/video_codec/RTCVideoEncoderFactoryH264.h b/sdk/objc/components/video_codec/RTCVideoEncoderFactoryH264.h
index d185656..c64405e 100644
--- a/sdk/objc/components/video_codec/RTCVideoEncoderFactoryH264.h
+++ b/sdk/objc/components/video_codec/RTCVideoEncoderFactoryH264.h
@@ -13,6 +13,6 @@
 #import "RTCMacros.h"
 #import "RTCVideoEncoderFactory.h"
 
-RTC_EXPORT
+RTC_OBJC_EXPORT
 @interface RTCVideoEncoderFactoryH264 : NSObject <RTCVideoEncoderFactory>
 @end
diff --git a/sdk/objc/components/video_codec/RTCVideoEncoderH264.h b/sdk/objc/components/video_codec/RTCVideoEncoderH264.h
index d57713e..a9c0558 100644
--- a/sdk/objc/components/video_codec/RTCVideoEncoderH264.h
+++ b/sdk/objc/components/video_codec/RTCVideoEncoderH264.h
@@ -14,7 +14,7 @@
 #import "RTCVideoCodecInfo.h"
 #import "RTCVideoEncoder.h"
 
-RTC_EXPORT
+RTC_OBJC_EXPORT
 @interface RTCVideoEncoderH264 : NSObject <RTCVideoEncoder>
 
 - (instancetype)initWithCodecInfo:(RTCVideoCodecInfo *)codecInfo;
diff --git a/sdk/objc/components/video_frame_buffer/RTCCVPixelBuffer.h b/sdk/objc/components/video_frame_buffer/RTCCVPixelBuffer.h
index a12bd7a..432a382 100644
--- a/sdk/objc/components/video_frame_buffer/RTCCVPixelBuffer.h
+++ b/sdk/objc/components/video_frame_buffer/RTCCVPixelBuffer.h
@@ -16,7 +16,7 @@
 NS_ASSUME_NONNULL_BEGIN
 
 /** RTCVideoFrameBuffer containing a CVPixelBufferRef */
-RTC_EXPORT
+RTC_OBJC_EXPORT
 @interface RTCCVPixelBuffer : NSObject <RTCVideoFrameBuffer>
 
 @property(nonatomic, readonly) CVPixelBufferRef pixelBuffer;