chrome/utility/media_galleries/ipc_data_source.h

// Copyright 2014 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 CHROME_UTILITY_MEDIA_GALLERIES_IPC_DATA_SOURCE_H_
#define CHROME_UTILITY_MEDIA_GALLERIES_IPC_DATA_SOURCE_H_

#include <stdint.h>

#include <string>

#include "base/memory/ref_counted.h"
#include "base/threading/thread_checker.h"
#include "chrome/common/extensions/media_parser.mojom.h"
#include "media/base/data_source.h"

namespace base {
class TaskRunner;
}

namespace metadata {

// Provides the metadata parser with blob data from the browser process. Class
// must be created and destroyed on the utility thread. Class may be used as a
// DataSource on a different thread. The utility thread must not be blocked
// for read operations to succeed.
class IPCDataSource : public media::DataSource {
 public:
  // May only be called on the utility thread.
  IPCDataSource(extensions::mojom::MediaDataSourcePtr media_data_source,
                int64_t total_size);
  ~IPCDataSource() override;

  // media::DataSource implementation. The methods may be called on any single
  // thread. First usage of these methods attaches a thread checker.
  void Stop() override;
  void Abort() override;
  void Read(int64_t position,
            int size,
            uint8_t* destination,
            const ReadCB& callback) override;
  bool GetSize(int64_t* size_out) override;
  bool IsStreaming() override;
  void SetBitrate(int bitrate) override;

 private:
  // Blob data read helpers: must be run on the utility thread.
  void ReadBlob(uint8_t* destination,
                const ReadCB& callback,
                int64_t position,
                int size);
  void ReadDone(uint8_t* destination,
                const ReadCB& callback,
                const std::vector<uint8_t>& data);

  extensions::mojom::MediaDataSourcePtr media_data_source_;
  const int64_t total_size_;

  scoped_refptr<base::TaskRunner> utility_task_runner_;

  base::ThreadChecker utility_thread_checker_;

  // Enforces that the DataSource methods are called on one other thread only.
  base::ThreadChecker data_source_thread_checker_;
};

}  // namespace metadata

#endif  // CHROME_UTILITY_MEDIA_GALLERIES_IPC_DATA_SOURCE_H_