iOS: Add interface for injecting custom shaders

webrtc/sdk/objc/Framework/Headers/WebRTC/RTCVideoViewShader.h

+/*
+ *  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 <Foundation/Foundation.h>
+
+#import <WebRTC/RTCVideoFrame.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+/**
+ * RTCVideoViewShader provides a way for apps to customize the OpenGL(ES) shaders used in
+ * rendering for the RTCEAGLVideoView/RTCNSGLVideoView.
+ */
+RTC_EXPORT
+@protocol RTCVideoViewShader

[daniela-webrtc, 2017/05/26 13:48:28]

It's common for protocols that encapsulate certain logical functionality and
that are not necessarily tied to certain class to use gerund form (...ing).
For instance NSCopying, NSLocking etc.
Also this should extend the NSObject protocol. (Named without ing because it
closely encapsulates functionality tied to the NSObject class) :)
So something like
@protocol RTCVideoViewShading : NSObject
@end

[magjed_webrtc, 2017/05/28 10:26:07]

Done.

+
+/** Callback for I420 frames. Each plane is given as a texture. */
+- (void)applyShadingForFrameWithRotation:(RTCVideoRotation)rotation
+                                  yPlane:(GLuint)yPlane
+                                  uPlane:(GLuint)uPlane
+                                  vPlane:(GLuint)vPlane;
+
+/** Callback for NV12 frames. Each plane is given as a texture. */
+- (void)applyShadingForFrameWithRotation:(RTCVideoRotation)rotation
+                                  yPlane:(GLuint)yPlane
+                                 uvPlane:(GLuint)uvPlane;
+
+@end
+
+NS_ASSUME_NONNULL_END