File manager: support for zipping selected files.

chrome/browser/resources/file_manager/js/butter_bar.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.
 
 /**
  * The minimum about of time to display the butter bar for, in ms.
  * Justification is 1000ms for minimum display time plus 300ms for transition
  * duration.
  */
 var MINIMUM_BUTTER_DISPLAY_TIME_MS = 1300;
@@ skipping 187 matching lines @@
   }
 };
 
 /**
  * @private
  * @return {string?} The type of operation.
  */
 ButterBar.prototype.transferType_ = function() {
   var progress = this.progress_;
   if (!progress ||
-      progress.pendingMoves === 0 && progress.pendingCopies === 0)
+      progress.pendingMoves === 0 && progress.pendingCopies === 0 &&
+      progress.pendingZips === 0)
     return 'TRANSFER';
 
+  if (progress.pendingZips > 0) {
+    return 'ZIP';
+  }
+
   if (progress.pendingMoves > 0) {
     if (progress.pendingCopies > 0)
       return 'TRANSFER';
     return 'MOVE';
   }
 
   return 'COPY';
 };
 
 /**
@@ skipping 164 matching lines @@
   }
 };
 
 /**
  * Undo the delete operation.
  * @private
  */
 ButterBar.prototype.undoDelete_ = function() {
   this.copyManager_.cancelDeleteTask(this.deleteTaskId_);
 };