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

services/video_capture/mojo_shared_memory_buffer_tracker.h

Index: services/video_capture/mojo_shared_memory_buffer_tracker.h
diff --git a/services/video_capture/mojo_shared_memory_buffer_tracker.h b/services/video_capture/mojo_shared_memory_buffer_tracker.h
new file mode 100644
index 0000000000000000000000000000000000000000..1a96e2b8996be708200174636149d178b725e07a
--- /dev/null
+++ b/services/video_capture/mojo_shared_memory_buffer_tracker.h
@@ -0,0 +1,37 @@
+// 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 SERVICES_VIDEO_CAPTURE_MOJO_SHARED_MEMORY_BUFFER_TRACKER_H_
+#define SERVICES_VIDEO_CAPTURE_MOJO_SHARED_MEMORY_BUFFER_TRACKER_H_
+
+#include "media/capture/video/video_capture_buffer_tracker.h"
+#include "media/mojo/common/mojo_shared_buffer_video_frame.h"
+
+namespace video_capture {
+
+// Tracker specifics for MojoSharedMemory.
+class MojoSharedMemoryBufferTracker final
+    : public media::VideoCaptureBufferTracker {
+ public:
+  MojoSharedMemoryBufferTracker();
+  ~MojoSharedMemoryBufferTracker() override;
+
+  // Implementation of media::VideoCaptureBufferTracker
+  bool Init(const gfx::Size& dimensions,
+            media::VideoPixelFormat format,
+            media::VideoPixelStorage storage_type,
+            base::Lock* lock) override;
+  std::unique_ptr<media::VideoCaptureBufferHandle> GetBufferHandle() override;
+  mojo::ScopedSharedBufferHandle GetHandleForTransit() override;
+
+ private:
+  friend class MojoSharedMemoryBufferHandle;
+
+  scoped_refptr<media::MojoSharedBufferVideoFrame> frame_;
+  size_t mapped_size_;
+};
+
+}  // namespace video_capture
+
+#endif  // SERVICES_VIDEO_CAPTURE_MOJO_SHARED_MEMORY_BUFFER_TRACKER_H_