Media Galleries API Metadata: Add audio video metadata extractor.

media/base/audio_video_metadata_extractor.h

+// Copyright 2013 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 MEDIA_BASE_MEDIA_FFMPEG_METADATA_EXTRACTOR_H_
+#define MEDIA_BASE_MEDIA_FFMPEG_METADATA_EXTRACTOR_H_
+
+#include <map>
+#include <string>
+
+#include "base/basictypes.h"
+#include "media/base/media_export.h"
+
+namespace media {
+
+class DataSource;
+
+// This class extracts a string dictionary of metadata tags for audio and video
+// files. It also provides the format name.
+class MEDIA_EXPORT AudioVideoMetadataExtractor {
+ public:
+  explicit AudioVideoMetadataExtractor(media::DataSource* source);
+  ~AudioVideoMetadataExtractor();
+
+  // Returns whether or not the fields were successfully extracted.
+  bool Extract();
+
+  const std::map<std::string, std::string>& GetTags();
+  const std::string& GetFormat();

[acolwell GONE FROM CHROMIUM, 2014/01/03 19:14:04]

nit: I think this should be removed. It unnecessarily leaks FFmpeg info and is
only used for testing.

[tommycli, 2014/01/03 23:08:36]

Done.

+  int GetDurationSeconds();

[acolwell GONE FROM CHROMIUM, 2014/01/03 19:14:04]

Use double or TimeDelta for this like the other media code does.

[tommycli, 2014/01/03 23:08:36]

Done.

+
+  // These functions return zero for containers with no video streams.
+  int GetWidth();

[acolwell GONE FROM CHROMIUM, 2014/01/03 19:14:04]

nit: s/GetWidth/width/ to match Chromium style for simple accessors.

[tommycli, 2014/01/03 23:08:36]

Done.

+  int GetHeight();
+
+ private:
+  media::DataSource* source_;
+
+  bool extracted_;
+  std::map<std::string, std::string> tags_;
+  std::string format_;
+  int duration_;
+
+  int width_;
+  int height_;
+
+  DISALLOW_COPY_AND_ASSIGN(AudioVideoMetadataExtractor);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_BASE_MEDIA_FFMPEG_METADATA_EXTRACTOR_H_