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

services/video_capture/mojo_shared_memory_buffer_tracker.cc

Index: services/video_capture/mojo_shared_memory_buffer_tracker.cc
diff --git a/services/video_capture/mojo_shared_memory_buffer_tracker.cc b/services/video_capture/mojo_shared_memory_buffer_tracker.cc
new file mode 100644
index 0000000000000000000000000000000000000000..4de53971b9de82ef401f827a7908d44b60e43e22
--- /dev/null
+++ b/services/video_capture/mojo_shared_memory_buffer_tracker.cc
@@ -0,0 +1,50 @@
+// 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_tracker.h"
+
+#include "base/memory/ptr_util.h"
+#include "services/video_capture/mojo_shared_memory_buffer_handle.h"
+
+namespace video_capture {
+
+MojoSharedMemoryBufferTracker::MojoSharedMemoryBufferTracker()
+    : VideoCaptureBufferTracker() {}
+
+MojoSharedMemoryBufferTracker::~MojoSharedMemoryBufferTracker() = default;
+
+bool MojoSharedMemoryBufferTracker::Init(const gfx::Size& dimensions,
+                                         media::VideoPixelFormat format,
+                                         media::VideoPixelStorage storage_type,
+                                         base::Lock* lock) {
+  if ((format != media::PIXEL_FORMAT_I420) ||
+      (storage_type != media::PIXEL_STORAGE_CPU)) {
+    LOG(ERROR) << "Unsupported pixel format or storage type";
+    return false;
+  }
+
+  set_dimensions(dimensions);
+  set_max_pixel_count(dimensions.GetArea());
+  set_pixel_format(format);
+  set_storage_type(storage_type);
+  mapped_size_ =
+      media::VideoCaptureFormat(dimensions, 0.0f, format, storage_type)
+          .ImageAllocationSize();
+
+  frame_ = media::MojoSharedBufferVideoFrame::CreateDefaultI420(
+      dimensions, base::TimeDelta());
+  return true;
+}
+
+std::unique_ptr<media::VideoCaptureBufferHandle>
+MojoSharedMemoryBufferTracker::GetBufferHandle() {
+  return base::MakeUnique<MojoSharedMemoryBufferHandle>(this);
+}
+
+mojo::ScopedSharedBufferHandle
+MojoSharedMemoryBufferTracker::GetHandleForTransit() {
+  return mojo::ScopedSharedBufferHandle();
+}
+
+}  // namespace video_capture