Fix ejecting if the element is not selected.

chrome/browser/resources/file_manager/foreground/js/file_manager_commands.js

 // 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 strict';
 
 /**
  * TODO(dzvorygin): Here we use this hack, since 'hidden' is standard
  * attribute and we can't use it's setter as usual.
  * @param {boolean} value New value of hidden property.
@@ skipping 359 matching lines @@
     }
     fileManager.volumeManager_.unmount(
         volumeInfo,
         function() {},
         errorCallback);
   },
   /**
    * @param {Event} event Command event.
    */
   canExecute: function(event, fileManager) {
-    var root = CommandUtil.getCommandEntry(this.fileManager_.navigationList);
-    var location =
-        root && this.fileManager_.volumeManager.getLocationInfo(root);
-    var rootType = location && location.isRootEntry && location.rootType;
+    var root = CommandUtil.getCommandEntry(event.target);
+    if (!root)
+      return;
+    var locationInfo = this.fileManager_.volumeManager.getLocationInfo(root);
+    var rootType =
+        locationInfo && locationInfo.isRootEntry && locationInfo.rootType;
 
     event.canExecute = (rootType == RootType.ARCHIVE ||
                         rootType == RootType.REMOVABLE);
     event.command.setHidden(!event.canExecute);
     event.command.label = rootType == RootType.ARCHIVE ?
         str('CLOSE_ARCHIVE_BUTTON_LABEL') :
         str('UNMOUNT_DEVICE_BUTTON_LABEL');
   }
 };
 
@@ skipping 443 matching lines @@
 /**
  * Reset the zoom factor.
  * @type {Command}
  */
 CommandHandler.COMMANDS_['zoom-reset'] = {
   execute: function(event, fileManager) {
     chrome.fileBrowserPrivate.zoom('reset');
   },
   canExecute: CommandUtil.canExecuteAlways
 };