iOS: Add interface for injecting custom shaders

webrtc/sdk/objc/Framework/Classes/RTCDefaultShaderDelegate.h

Index: webrtc/sdk/objc/Framework/Classes/RTCDefaultShaderDelegate.h
diff --git a/webrtc/sdk/objc/Framework/Classes/RTCNV12TextureCache.h b/webrtc/sdk/objc/Framework/Classes/RTCDefaultShaderDelegate.h
similarity index 58%
copy from webrtc/sdk/objc/Framework/Classes/RTCNV12TextureCache.h
copy to webrtc/sdk/objc/Framework/Classes/RTCDefaultShaderDelegate.h
index 0aa7a5718177b01678622b550cc001fdb290bd31..000094c4c8d31270135ac67d48ea88144701bdc1 100644
--- a/webrtc/sdk/objc/Framework/Classes/RTCNV12TextureCache.h
+++ b/webrtc/sdk/objc/Framework/Classes/RTCDefaultShaderDelegate.h
@@ -8,22 +8,11 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#import <GLKit/GLKit.h>
-
-@class RTCVideoFrame;
+#import "WebRTC/RTCVideoViewShaderDelegate.h"
 
 NS_ASSUME_NONNULL_BEGIN
 
-@interface RTCNV12TextureCache : NSObject
-
-@property(nonatomic, readonly) GLuint yTexture;
-@property(nonatomic, readonly) GLuint uvTexture;
-
-- (nullable instancetype)initWithContext:(EAGLContext *)context;
-
-- (BOOL)uploadFrameToTextures:(RTCVideoFrame *)frame;
-
-- (void)releaseTextures;
+@interface RTCDefaultShaderDelegate : NSObject <RTCVideoViewShaderDelegate>
 
 @end