File manager: support for zipping selected files.

chrome/browser/resources/file_manager/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.
 
 var CommandUtil = {};
 
 /**
  * Extracts root on which command event was dispatched.
  *
  * @param {Event} event Command event for which to retrieve root to operate on.
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           function(task) {
             tasks.execute(task.taskId);
           });
     }
   },
   canExecute: function(event, fileManager) {
     var tasks = fileManager.getSelection().tasks;
     event.canExecute = tasks && tasks.size() > 1;
   }
 };
+
+/**
+ * Creates zip file for current selection.
+ */
+Commands.zipSelectionCommand = {
+  execute: function(event, fileManager) {
+    var dirEntry = fileManager.directoryModel_.getCurrentDirEntry();
+    var selectionEntries = fileManager.getSelection().entries;
+    fileManager.copyManager_.zipSelection(dirEntry, fileManager.isOnGData(),
+                                          selectionEntries);
+  },
+  canExecute: function(event, fileManager) {
+    var selection = fileManager.getSelection();
+    event.canExecute = !fileManager.isOnGData() && selection &&
+        selection.totalCount > 0;
+  }
+};