chrome/utility/media_galleries/media_metadata_parser.h

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CHROME_UTILITY_MEDIA_GALLERIES_MEDIA_METADATA_PARSER_H_
   6 #define CHROME_UTILITY_MEDIA_GALLERIES_MEDIA_METADATA_PARSER_H_
   7
   8 #include "base/callback.h"
   9 #include "base/memory/scoped_ptr.h"
  10 #include "chrome/common/extensions/api/media_galleries.h"
  11
  12 namespace base {
  13 class Thread;
  14 }
  15
  16 namespace media {
  17 class DataSource;
  18 }
  19
  20 namespace metadata {
  21
  22 // This class takes a MIME type and data source and parses its metadata. It
  23 // handles audio, video, and images. It delegates its operations to FFMPEG,
  24 // libexif, etc. This class lives and operates on the utility thread of the
  25 // utility process, as we wish to sandbox potentially dangerous operations
  26 // on user-provided data.
  27 class MediaMetadataParser {
  28  public:
  29   typedef extensions::api::media_galleries::MediaMetadata MediaMetadata;
  30   typedef base::Callback<void(scoped_ptr<MediaMetadata>)> MetadataCallback;
  31
  32   // Does not take ownership of |source|. Caller is responsible for ensuring
  33   // that |source| outlives this object.
  34   MediaMetadataParser(media::DataSource* source, const std::string& mime_type);
  35
  36   ~MediaMetadataParser();
  37
  38   // |callback| is called on same message loop.
  39   void Start(const MetadataCallback& callback);
  40
  41  private:
  42   // Only accessed on |media_thread_| from this class.
  43   media::DataSource* const source_;
  44
  45   const std::string mime_type_;
  46
  47   // Thread that blocking media parsing operations run on while the main thread
  48   // handles messages from the browser process.
  49   // TODO(tommycli): Replace with a reference to a WorkerPool if we ever use
  50   // this class in batch mode.
  51   scoped_ptr<base::Thread> media_thread_;
  52
  53   DISALLOW_COPY_AND_ASSIGN(MediaMetadataParser);
  54 };
  55
  56 }  // namespace metadata
  57
  58 #endif  // CHROME_UTILITY_MEDIA_GALLERIES_MEDIA_METADATA_PARSER_H_