[ew] Simplify the entry watcher logic.

storage/browser/fileapi/watcher_manager.h

Index: storage/browser/fileapi/watcher_manager.h
diff --git a/storage/browser/fileapi/watcher_manager.h b/storage/browser/fileapi/watcher_manager.h
index 40f3733c05cc86d84b19489f6fe83cf51d1af98e..1c4f3d1a76ec7658b937ca21a5bc220b4644f625 100644
--- a/storage/browser/fileapi/watcher_manager.h
+++ b/storage/browser/fileapi/watcher_manager.h
@@ -27,35 +27,24 @@ class FileSystemURL;
 // can assume that they don't get any null callbacks.
 class WatcherManager {
  public:
-  typedef base::Callback<void(base::File::Error result)> StatusCallback;
-
-  // Observes watched entries.
-  class Observer {
-   public:
-    Observer() {}
-    virtual ~Observer() {}
-
-    // Notifies about an entry represented by |url| being changed.
-    virtual void OnEntryChanged(const FileSystemURL& url) = 0;
+  enum Action { CHANGED, REMOVED };
 
-    // Notifies about an entry represented by |url| being removed.
-    virtual void OnEntryRemoved(const FileSystemURL& url) = 0;
-  };
+  typedef base::Callback<void(base::File::Error result)> StatusCallback;
+  typedef base::Callback<void(Action action)> NotificationCallback;
 
   virtual ~WatcherManager() {}
 
-  virtual void AddObserver(Observer* observer) = 0;
-  virtual void RemoveObserver(Observer* observer) = 0;
-  virtual bool HasObserver(Observer* observer) const = 0;
-
   // Observes a directory entry. If the |recursive| mode is not supported then
   // FILE_ERROR_INVALID_OPERATION must be returned as an error. If the |url| is
   // already watched, or setting up the watcher fails, then |callback|
   // must be called with a specific error code. Otherwise |callback| must be
-  // called with the FILE_OK error code.
-  virtual void WatchDirectory(const FileSystemURL& url,
-                              bool recursive,
-                              const StatusCallback& callback) = 0;
+  // called with the FILE_OK error code. |notification_callback| is called for
+  // every change related to the watched directory.
+  virtual void WatchDirectory(

[benwells, 2014/10/23 02:10:34]

Is this implemented / called by anything?

[mtomasz, 2014/10/23 02:15:11]

Not now, but I'll need it for upcoming CLs. FSP code is going to implement this
interface. chrome.fileManagerPrivate will use fsp's implementation of it to set
watchers.

In the future watcher logic in chrome.fileManagerPrivate will be replaced with
Entry Watcher API.

+      const FileSystemURL& url,
+      bool recursive,
+      const StatusCallback& callback,
+      const NotificationCallback& notification_callback) = 0;
 
   // Stops observing an entry represented by |url|.
   virtual void UnwatchEntry(const FileSystemURL& url,