iOS/MacOS:Refactor metal rendering by extracting common implementation

webrtc/sdk/objc/Framework/Classes/Metal/RTCMTLRenderer.h

Index: webrtc/sdk/objc/Framework/Classes/Metal/RTCMTLRenderer.h
diff --git a/webrtc/sdk/objc/Framework/Classes/Metal/RTCMTLNV12Renderer.h b/webrtc/sdk/objc/Framework/Classes/Metal/RTCMTLRenderer.h
similarity index 76%
copy from webrtc/sdk/objc/Framework/Classes/Metal/RTCMTLNV12Renderer.h
copy to webrtc/sdk/objc/Framework/Classes/Metal/RTCMTLRenderer.h
index 4f7b25eefa7857af41b41729305b8e579259666a..e279b098b55ac7cb35503f3e6df913b0b360f83b 100644
--- a/webrtc/sdk/objc/Framework/Classes/Metal/RTCMTLNV12Renderer.h
+++ b/webrtc/sdk/objc/Framework/Classes/Metal/RTCMTLRenderer.h
@@ -9,14 +9,19 @@
  */
 
 #import <Foundation/Foundation.h>
-#import <MetalKit/MTKView.h>
+#if TARGET_OS_IPHONE
+#import <UIKit/UIKit.h>
+#else
+#import <AppKit/AppKit.h>
+#endif
 
 #import "WebRTC/RTCVideoFrame.h"
 
+NS_ASSUME_NONNULL_BEGIN
 /**
  * Protocol defining ability to render RTCVideoFrame in Metal enabled views.
  */
-@protocol RTCMTLRenderer <NSObject>
+@protocol RTCMTLRenderer<NSObject>
 
 /**
  * Method to be implemented to perform actual rendering of the provided frame.
@@ -31,13 +36,20 @@
  * If not possible method returns NO and callers of the method are responisble for performing
  * cleanups.
  */
+
+#if TARGET_OS_IOS
 - (BOOL)addRenderingDestination:(__kindof UIView *)view;
+#else
+- (BOOL)addRenderingDestination:(__kindof NSView *)view;
+#endif
 
 @end
 
 /**
  * Implementation of RTCMTLRenderer protocol for rendering native nv12 video frames.
  */
-@interface RTCMTLNV12Renderer : NSObject <RTCMTLRenderer>
-
+NS_AVAILABLE(10_11, 9_0)
+@interface RTCMTLRenderer : NSObject<RTCMTLRenderer>
 @end
+
+NS_ASSUME_NONNULL_END