iOS: Add interface for injecting custom shaders

webrtc/sdk/objc/Framework/Classes/RTCI420TextureCache.mm

 /*
  *  Copyright 2017 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 "RTCI420TextureCache.h"
 
-#import "RTCShader+Private.h"
+#if TARGET_OS_IPHONE
+#import <OpenGLES/ES3/gl.h>
+#else
+#import <OpenGL/gl3.h>
+#endif
 
 #include <vector>
 
 // Two sets of 3 textures are used here, one for each of the Y, U and V planes. Having two sets
 // alleviates CPU blockage in the event that the GPU is asked to render to a texture that is already
 // in use.
 static const GLsizei kNumTextureSets = 2;
 static const GLsizei kNumTexturesPerSet = 3;
 static const GLsizei kNumTextures = kNumTexturesPerSet * kNumTextureSets;
 
@@ skipping 116 matching lines @@
              stride:frame.strideU];
 
   [self uploadPlane:frame.dataV
             texture:self.vTexture
               width:chromaWidth
              height:chromaHeight
              stride:frame.strideV];
 }
 
 @end