[Mojo Video Capture] Simplify media::VideoCaptureDevice::Client:Buffer to a struct

media/capture/video/shared_memory_buffer_tracker.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MEDIA_CAPTURE_VIDEO_SHARED_MEMORY_BUFFER_TRACKER_H_
 #define MEDIA_CAPTURE_VIDEO_SHARED_MEMORY_BUFFER_TRACKER_H_
 
 #include "media/capture/video/video_capture_buffer_tracker.h"
 
 namespace media {
 
 class SharedMemoryBufferHandle;
 
 // Tracker specifics for SharedMemory.
 class SharedMemoryBufferTracker final : public VideoCaptureBufferTracker {
  public:
   SharedMemoryBufferTracker();
 
   bool Init(const gfx::Size& dimensions,
             VideoPixelFormat format,
             VideoPixelStorage storage_type,
             base::Lock* lock) override;
 
-  std::unique_ptr<VideoCaptureBufferHandle> GetBufferHandle() override;
+  std::unique_ptr<VideoCaptureBufferHandle> GetReadWriteAccess() override;
   mojo::ScopedSharedBufferHandle GetHandleForTransit() override;
 
  private:
   friend class SharedMemoryBufferHandle;
 
   // The memory created to be shared with renderer processes.
   base::SharedMemory shared_memory_;
   size_t mapped_size_;
 };
 
 // A simple proxy that implements the BufferHandle interface, providing
 // accessors to SharedMemTracker's memory and properties.
 class SharedMemoryBufferHandle : public VideoCaptureBufferHandle {
  public:
   // |tracker| must outlive SimpleBufferHandle. This is ensured since a
   // tracker is pinned until ownership of this SimpleBufferHandle is returned
   // to VideoCaptureBufferPool.
   explicit SharedMemoryBufferHandle(SharedMemoryBufferTracker* tracker);
   ~SharedMemoryBufferHandle() override;
 
-  gfx::Size dimensions() const override;
   size_t mapped_size() const override;
-  void* data(int plane) override;
-#if defined(OS_POSIX) && !defined(OS_MACOSX)
-  base::FileDescriptor AsPlatformFile() override;
-#endif
-  bool IsBackedByVideoFrame() const override;
-  scoped_refptr<VideoFrame> GetVideoFrame() override;
+  uint8_t* data() override;
+  const uint8_t* data() const override;
 
  private:
   SharedMemoryBufferTracker* const tracker_;
 };
 
 }  // namespace media
 
 #endif  // MEDIA_CAPTURE_VIDEO_SHARED_MEMORY_BUFFER_TRACKER_H_