Rename some cricket::VideoFrame methods, to align with webrtc::VideoFrame.

webrtc/api/objc/RTCVideoFrame.mm

 /*
  *  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.
  */
 
@@ skipping 74 matching lines @@
 }
 
 - (CVPixelBufferRef)nativeHandle {
   return static_cast<CVPixelBufferRef>(_videoFrame->GetNativeHandle());
 }
 
 - (void)convertBufferIfNeeded {
   if (!_i420Buffer) {
     if (_videoFrame->GetNativeHandle()) {
       // Convert to I420.
-      _i420Buffer = _videoFrame->GetVideoFrameBuffer()->NativeToI420Buffer();
+      _i420Buffer = _videoFrame->video_frame_buffer()->NativeToI420Buffer();
     } else {
       // Should already be I420.
-      _i420Buffer = _videoFrame->GetVideoFrameBuffer();
+      _i420Buffer = _videoFrame->video_frame_buffer();
     }
   }
 }
 
 #pragma mark - Private
 
 - (instancetype)initWithNativeFrame:(const cricket::VideoFrame *)nativeFrame {
   if (self = [super init]) {
     // Keep a shallow copy of the video frame. The underlying frame buffer is
     // not copied.
     _videoFrame.reset(nativeFrame->Copy());
   }
   return self;
 }
 
 - (rtc::scoped_refptr<webrtc::VideoFrameBuffer>)i420Buffer {
   [self convertBufferIfNeeded];
   return _i420Buffer;
 }
 
 @end