Storage manager: Hide "Offline files" when Google Drive volume is not mounted.

chrome/browser/resources/options/chromeos/storage_manager.js

 // Copyright 2016 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.
 
 /**
  * Enumeration for device state about remaining space.
  * These values must be kept in sync with
  * StorageManagerHandler::StorageSpaceState in C++ code.
  * @enum {number}
  * @const
@@ skipping 113 matching lines @@
       $('storage-manager-size-downloads').textContent = size;
     },
 
     /**
      * Updates the size of Google Drive offline files.
      * @param {string} size Formatted string of the size of Google Drive offline
      *     files.
      * @private
      */
     setDriveCacheSize_: function(size) {
+      assert(!$('storage-manager-item-drive-cache').hidden);
       $('storage-manager-size-drive-cache').textContent = size;
     },
 
     /**
      * Updates the size of browsing data.
      * @param {string} size Formatted string of the size of browsing data.
      * @private
      */
     setBrowsingDataSize_: function(size) {
       $('storage-manager-size-browsing-data').textContent = size;
@@ skipping 13 matching lines @@
      * @param {string} size Formatted string of the size of Android apps and
      * cache.
      * @private
      */
     setArcSize_: function(size) {
       assert(!$('storage-manager-item-arc').hidden);
       $('storage-manager-size-arc').textContent = size;
     },
 
     /**
+     * Shows the item "Offline files" on the overlay UI.
+     * @private
+     */
+    showDriveCacheItem_: function() {
+      $('storage-manager-item-drive-cache').hidden = false;
+    },
+
+    /**
      * Shows the item "Android apps and cache" on the overlay UI.
      * @private
      */
     showArcItem_: function() {
       $('storage-manager-item-arc').hidden = false;
     },
 
     /**
      * Starts periodical update for storage usage.
      * @private
@@ skipping 21 matching lines @@
 
   // Forward public APIs to private implementations.
   cr.makePublic(StorageManager, [
     'setArcSize',
     'setBrowsingDataSize',
     'setDownloadsSize',
     'setDriveCacheSize',
     'setOtherUsersSize',
     'setSizeStat',
     'showArcItem',
+    'showDriveCacheItem',
   ]);
 
   return {
     StorageManager: StorageManager
   };
 });