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

services/video_capture/mojo_shared_memory_buffer_handle.cc

-// 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.
-
-#include "services/video_capture/mojo_shared_memory_buffer_handle.h"
-
-#include "services/video_capture/mojo_shared_memory_buffer_tracker.h"
-
-namespace video_capture {
-
-MojoSharedMemoryBufferHandle::MojoSharedMemoryBufferHandle(
-    MojoSharedMemoryBufferTracker* tracker)
-    : tracker_(tracker) {}
-
-MojoSharedMemoryBufferHandle::~MojoSharedMemoryBufferHandle() = default;
-
-gfx::Size MojoSharedMemoryBufferHandle::dimensions() const {
-  return tracker_->dimensions();
-}
-
-size_t MojoSharedMemoryBufferHandle::mapped_size() const {
-  return tracker_->mapped_size_;
-}
-
-void* MojoSharedMemoryBufferHandle::data(int plane) {
-  DCHECK_GE(plane, 0);
-  return tracker_->frame_->data(static_cast<size_t>(plane));
-}
-
-#if defined(OS_POSIX) && !defined(OS_MACOSX)
-base::FileDescriptor MojoSharedMemoryBufferHandle::AsPlatformFile() {
-  NOTREACHED();
-  return base::FileDescriptor();
-}
-#endif
-
-bool MojoSharedMemoryBufferHandle::IsBackedByVideoFrame() const {
-  return true;
-}
-
-scoped_refptr<media::VideoFrame> MojoSharedMemoryBufferHandle::GetVideoFrame() {
-  return tracker_->frame_;
-}
-
-}  // namespace video_capture