iOS render: Handle frame rotation in OpenGL

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

 /*
  *  Copyright 2015 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 <AVFoundation/AVFoundation.h>
 #import <Foundation/Foundation.h>
 
 #import <WebRTC/RTCMacros.h>
 
 NS_ASSUME_NONNULL_BEGIN
 
 // RTCVideoFrame is an ObjectiveC version of cricket::VideoFrame.
 RTC_EXPORT
 @interface RTCVideoFrame : NSObject
 
 /** Width without rotation applied. */
 @property(nonatomic, readonly) size_t width;
 
 /** Height without rotation applied. */
 @property(nonatomic, readonly) size_t height;
+@property(nonatomic, readonly) int rotation;
 @property(nonatomic, readonly) size_t chromaWidth;
 @property(nonatomic, readonly) size_t chromaHeight;
 // These can return NULL if the object is not backed by a buffer.
 @property(nonatomic, readonly, nullable) const uint8_t *yPlane;
 @property(nonatomic, readonly, nullable) const uint8_t *uPlane;
 @property(nonatomic, readonly, nullable) const uint8_t *vPlane;
 @property(nonatomic, readonly) int32_t yPitch;
 @property(nonatomic, readonly) int32_t uPitch;
 @property(nonatomic, readonly) int32_t vPitch;
 
 /** Timestamp in nanoseconds. */
-@property(nonatomic, readonly) int64_t timeStamp;
+@property(nonatomic, readonly) int64_t timeStampNs;
 
 /** The native handle should be a pixel buffer on iOS. */
 @property(nonatomic, readonly) CVPixelBufferRef nativeHandle;
 
 - (instancetype)init NS_UNAVAILABLE;
 
 /** If the frame is backed by a CVPixelBuffer, creates a backing i420 frame.
  *  Calling the yuv plane properties will call this method if needed.
  */
 - (void)convertBufferIfNeeded;
 
 @end
 
 NS_ASSUME_NONNULL_END