Implement mediaGalleriesPrivate api to notify extensions about gallery changed events.

chrome/browser/extensions/api/media_galleries_private/gallery_watch_manager.h

Index: chrome/browser/extensions/api/media_galleries_private/gallery_watch_manager.h
diff --git a/chrome/browser/extensions/api/media_galleries_private/gallery_watch_manager.h b/chrome/browser/extensions/api/media_galleries_private/gallery_watch_manager.h
new file mode 100644
index 0000000000000000000000000000000000000000..c231d1831ba3ae87e26f211af86947c26b8b7514
--- /dev/null
+++ b/chrome/browser/extensions/api/media_galleries_private/gallery_watch_manager.h
@@ -0,0 +1,141 @@
+// 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.
+
+// Manages all the gallery file watchers for the associated profile. This
+// is temporary and will be moved to a permanent, public place in the near
+// future.
+
+#ifndef CHROME_BROWSER_EXTENSIONS_API_MEDIA_GALLERIES_PRIVATE_GALLERY_WATCH_MANAGER_H_
+#define CHROME_BROWSER_EXTENSIONS_API_MEDIA_GALLERIES_PRIVATE_GALLERY_WATCH_MANAGER_H_
+
+#include <map>
+#include <set>
+#include <string>
+
+#include "base/file_path.h"
+#include "base/files/file_path_watcher.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
+#include "base/threading/thread_checker.h"
+#include "base/time.h"
+
+class Profile;
+
+namespace extensions {
+
+// The profile-keyed service that manages the gallery watchers. This class is
+// constructed, destructed and operated on the FILE thread.

[Lei Zhang, 2012/12/15 01:11:54]

You can just say "this class lives on the foo thread".

[kmadhusu, 2012/12/17 23:58:05]

Done.

+class GalleryWatchManager {
+ public:
+  typedef std::set<std::string> ExtensionIdSet;

[Lei Zhang, 2012/12/15 01:11:54]

This seems to be used in 1 place inside the .cc file.

[kmadhusu, 2012/12/17 23:58:05]

Removed typedef.

+
+  explicit GalleryWatchManager(const Profile* profile);
+  ~GalleryWatchManager();
+
+  // Initiates a gallery watch operation for the extension specified by
+  // the |extension_id|. |gallery_id| specifies the gallery identifier and
+  // |watch_path| specifies the absolute path of the gallery. Returns true,
+  // if the watch was set successfully.
+  bool StartGalleryWatch(const std::string& gallery_id,
+                         const FilePath& watch_path,
+                         const std::string& extension_id);
+
+  // Cancels the gallery watch operation for the extension specified by the
+  // |extension_id|. |watch_path| specifies the gallery absolute path.
+  void StopGalleryWatch(const FilePath& watch_path,
+                        const std::string& extension_id);
+
+  // Handles the extension unloaded/uninstalled/destroyed event.
+  void OnExtensionDestroyed(const std::string& extension_id);
+
+ private:
+  typedef std::map<std::string, int> ExtensionUsageRegistry;

[Lei Zhang, 2012/12/15 04:13:21]

This map is too wimpy to a registry.

[kmadhusu, 2012/12/17 23:58:05]

ExtensionUsageRegistry => ExtensionWatchCountMap

+
+  class GalleryFilePathWatcher;
+  typedef std::map<FilePath, GalleryFilePathWatcher*> WatcherMap;
+
+  // Gallery file path watcher delegate to handle the gallery change

[Lei Zhang, 2012/12/15 04:13:21]

You should mention this class does recursive watches.

[kmadhusu, 2012/12/17 23:58:05]

Done.

+  // notifications. This class manages all the extension usage and forwards
+  // the gallery change notifications to the extensions.
+  // This class is constructed, destructed and operated on the FILE thread.
+  // This class is instantiated per gallery watch path.
+  class GalleryFilePathWatcher {

[Lei Zhang, 2012/12/15 04:13:21]

Can this go in the .cc file instead?

[kmadhusu, 2012/12/17 23:58:05]

Done.

+   public:
+    GalleryFilePathWatcher(const Profile* profile,
+                           const std::string& gallery_id,
+                           const FilePath& path,
+                           const std::string& extension_id);
+
+    ~GalleryFilePathWatcher();
+
+    // Adds the extension specified by the |extension_id| to the
+    // ExtensionUsageRegistry and initiate the watch operation.
+    void AddExtension(const std::string& extension_id);
+
+    // Cancels the watch for the extension specified by the |extension_id|.
+    void RemoveExtension(const std::string& extension_id);
+
+    // Handles the extension unloaded/uninstalled/destroyed event.
+    void OnExtensionDestroyed(const std::string& extension_id);
+
+    // Returns the total number of watchers for the |gallery_path_|.
+    unsigned int GetRefCount() const;
+
+    // Sets up the watch operation for the specified |gallery_path_|. On
+    // success, returns true.
+    bool SetupWatch();
+
+   private:
+    // FilePathWatcher callback.
+    void OnFilePathChanged(const FilePath& path, bool error);
+
+    // Current profile.
+    const Profile* profile_;
+
+    // The gallery identifier, e.g "1".
+    const std::string gallery_id_;
+
+    // The gallery file path watcher.
+    scoped_ptr<base::files::FilePathWatcher> file_watcher_;

[Lei Zhang, 2012/12/15 04:13:21]

Does this need to be a scoped_ptr?

[kmadhusu, 2012/12/17 23:58:05]

Not needed.

+
+    // The gallery file path, e.g "C:/My Pictures".

[Lei Zhang, 2012/12/15 04:13:21]

nit: C:\, not C:/

[kmadhusu, 2012/12/17 23:58:05]

Done.

+    FilePath gallery_path_;
+
+    // Map to keep track of the extension and its corresponding watch count.
+    // Key: Extension identifier, e.g "qoueruoweuroiwueroiwujkshdf".
+    // Value: Number of watchers in this extension, e.g "3".
+    ExtensionUsageRegistry extensions_;

[Lei Zhang, 2012/12/15 04:13:21]

|extensions_watch_count_map_| ?

[kmadhusu, 2012/12/17 23:58:05]

Done.

+
+    // Total number of watchers.
+    unsigned int ref_count_;

[Lei Zhang, 2012/12/15 04:13:21]

Do you have to manually refcount?

[kmadhusu, 2012/12/17 23:58:05]

Fixed. GalleryFilePathWatch inherits from RefCounted class.

+
+    // Used to manage the gallery changed events.
+    base::Time last_gallery_changed_event_;

[Lei Zhang, 2012/12/15 04:13:21]

This should be per-extension.

Extension AA has a watch for /foo, and an event happens at T=0. If extension BB
adds a watch for /foo at T=1, and an event happens at T=2, BB will never be
notified.

[kmadhusu, 2012/12/17 23:58:05]

Done.

+
+    // Make sure all the member functions are called on the right thread.
+    base::ThreadChecker thread_check_;
+
+    // Used to provide a weak pointer to FilePathWatcher callback.
+    base::WeakPtrFactory<GalleryFilePathWatcher> weak_ptr_factory_;
+
+    DISALLOW_COPY_AND_ASSIGN(GalleryFilePathWatcher);
+  };
+
+  // Current profile.
+  const Profile* profile_;
+
+  // Map to manage the gallery file path watchers.
+  // Key: Gallery watch path.
+  // Value: GalleryFilePathWatcher*.
+  WatcherMap gallery_watchers_;
+
+  // Make sure all the member functions are called on the right thread.
+  base::ThreadChecker thread_checker_;
+
+  DISALLOW_COPY_AND_ASSIGN(GalleryWatchManager);
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_API_MEDIA_GALLERIES_PRIVATE_GALLERY_WATCH_MANAGER_H_