[SystemInfo API] Rewrite storage info provider using storage monitor impl.

chrome/common/extensions/api/experimental_system_info_storage.idl

 // 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.
 
 // Use the <code>chrome.experimental.systemInfo.storage</code> API to query
 // storage device information and be notified when it changes.
 namespace experimental.systemInfo.storage {
 
   enum StorageUnitType {
     // The storage has fixed media, e.g. hard disk or SSD.
     fixed,
     // The storage is removable, e.g. USB flash drive.
     removable,
     // The storage type is unknown.
     unknown
   };
 
   dictionary StorageUnitInfo {
-    // The unique id of the storage unit.
+    // The unique storage id. It will use the transient ID.
     DOMString id;
+    // The name of the storage unit.
+    DOMString name;
     // The media type of the storage unit.
     StorageUnitType type;
     // The total amount of the storage space, in bytes.
+    // Default value is 0 if query operation fails.
     double capacity;
     // The available amount of the storage space, in bytes.
+    // Default value is 0 if query operation fails.
     double availableCapacity;
   };
 
-  dictionary StorageChangeInfo {
-    // The uniue id of the storage unit already changed.
+  dictionary StorageFreeSpaceChangeInfo {
+    // The transient id of the storage unit already changed.
     DOMString id;
     // The new value of the available capacity.
     double availableCapacity;
   };
 
   // A dictionary that describes the add particular storage device watch
   // request results.
   dictionary AddWatchResult {
     DOMString id;
     boolean success;
@@ skipping 19 matching lines @@
     // Get all the watched storage devices.
     static void getAllWatch(GetAllWatchCallback callback);
 
     // Remove all the storage devices monitors.
     static void removeAllWatch();
   };
 
   interface Events {
     // Fired when the storage device available capacity is changed.
     // |info|: The changed information for the specified storage unit.
-    static void onAvailableCapacityChanged(StorageChangeInfo info);
+    static void onAvailableCapacityChanged(StorageFreeSpaceChangeInfo info);
 
     // Fired when a new removable storage is attached to the system.
     static void onAttached(StorageUnitInfo info);
 
     // Fired when a removable storage is detached from the system.
     static void onDetached(DOMString id);
   };
 
 };