Media Gallery: Implement a basic version of GetMediaFileSystems().

chrome/browser/media_gallery/media_device_manager.h

+// Copyright (c) 2012 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.
+
+// MediaDeviceManager registers pictures directories as File API filesystems
+// and keeps track of the path to filesystem ID mappings.
+// In the near future, MediaDeviceManager will also support media devices.
+
+#ifndef CHROME_BROWSER_MEDIA_GALLERY_MEDIA_DEVICE_MANAGER_H_
+#define CHROME_BROWSER_MEDIA_GALLERY_MEDIA_DEVICE_MANAGER_H_
+#pragma once
+
+#include <map>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/lazy_instance.h"
+
+class FilePath;
+
+namespace fileapi {
+class IsolatedContext;
+}
+
+namespace chrome {
+
+class MediaDeviceManager {

[vandebo (ex-Chrome), 2012/05/23 00:50:46]

nit: MediaFileSystemsManager / MediaFileSystemRegistry

[Lei Zhang, 2012/05/23 03:12:49]

Sure, MediaFileSystemRegistry it is.

+ public:
+  // (Filesystem ID, path)
+  typedef std::pair<std::string, FilePath> MediaFSIDAndPath;
+
+  // The instance is lazily created per browser process.
+  static MediaDeviceManager* GetInstance();
+
+  // Returns the list of media filesystem IDs and paths.
+  // Called on the UI thread.
+  std::vector<MediaFSIDAndPath>* GetMediaFileSystems();

[vandebo (ex-Chrome), 2012/05/23 00:50:46]

I think (you may want to check with others), that because of Return Value
Optimization, you don't need to return a pointer to the vector, just return the
vector.

[Lei Zhang, 2012/05/23 03:12:49]

Done. I see a few other places that do this and cited RVO as the reason.

+
+ private:
+  friend struct base::DefaultLazyInstanceTraits<MediaDeviceManager>;
+
+  // Mapping of media directories to filesystem IDs.
+  typedef std::map<FilePath, std::string> MediaPathToFSIDMap;
+
+  // Obtain an instance of this class via GetInstance().
+  MediaDeviceManager();
+  virtual ~MediaDeviceManager();
+
+  // Registers a path as a media file system.
+  void RegisterPathAsFileSystem(const FilePath& path);
+
+  MediaPathToFSIDMap media_fs_map_;
+
+  DISALLOW_COPY_AND_ASSIGN(MediaDeviceManager);
+};
+
+}  // namespace chrome
+
+#endif  // CHROME_BROWSER_MEDIA_GALLERY_MEDIA_DEVICE_MANAGER_H_