[fsp] Pass more detailed errors to the providing extension.

chrome/browser/chromeos/file_system_provider/provided_file_system_interface.h

 // Copyright 2014 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 CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_PROVIDED_FILE_SYSTEM_INTERFACE_H_
 #define CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_PROVIDED_FILE_SYSTEM_INTERFACE_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 180 matching lines @@
 
   // Requests removing a watcher, which is immediately deleted from the internal
   // list, hence the operation is not abortable.
   virtual void RemoveWatcher(
       const GURL& origin,
       const base::FilePath& entry_path,
       bool recursive,
       const storage::AsyncFileUtil::StatusCallback& callback) = 0;
 
   // Notifies about changes related to the watcher within the file system.
-  // Invoked by the file system implementation. Returns false if the
-  // notification arguments are malformed or the entry is not watched anymore.
+  // Invoked by the file system implementation. Returns an error code via the
+  // callback if the notification arguments are malformed or the entry is not
+  // watched anymore. On success, returns base::File::FILE_OK.
   // TODO(mtomasz): Replace [entry_path, recursive] with a watcher id.
-  virtual bool Notify(const base::FilePath& entry_path,
-                      bool recursive,
-                      storage::WatcherManager::ChangeType change_type,
-                      scoped_ptr<ProvidedFileSystemObserver::Changes> changes,
-                      const std::string& tag) = 0;
+  virtual void Notify(
+      const base::FilePath& entry_path,
+      bool recursive,
+      storage::WatcherManager::ChangeType change_type,
+      scoped_ptr<ProvidedFileSystemObserver::Changes> changes,
+      const std::string& tag,
+      const storage::AsyncFileUtil::StatusCallback& callback) = 0;
 
   // Returns a provided file system info for this file system.
   virtual const ProvidedFileSystemInfo& GetFileSystemInfo() const = 0;
 
   // Returns a mutable list of watchers.
   virtual Watchers* GetWatchers() = 0;
 
   // Returns a request manager for the file system.
   virtual RequestManager* GetRequestManager() = 0;
 
   // Adds an observer on the file system.
   virtual void AddObserver(ProvidedFileSystemObserver* observer) = 0;
 
   // Removes an observer.
   virtual void RemoveObserver(ProvidedFileSystemObserver* observer) = 0;
 
   // Returns a weak pointer to this object.
   virtual base::WeakPtr<ProvidedFileSystemInterface> GetWeakPtr() = 0;
 };
 
 }  // namespace file_system_provider
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_PROVIDED_FILE_SYSTEM_INTERFACE_H_