Cancel previous scan when replacing the directory contents.

chrome/browser/resources/file_manager/js/directory_model.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.
 
 // If directory files changes too often, don't rescan directory more than once
 // per specified interval
 var SIMULTANEOUS_RESCAN_INTERVAL = 1000;
 // Used for operations that require almost instant rescan.
 var SHORT_RESCAN_INTERVAL = 100;
 
@@ skipping 369 matching lines @@
  *
  * This should be used when changing directory or initiating a new search.
  *
  * @private
  * @param {DirectoryContentes} newDirContents New DirectoryContents instance to
  *     replace currentDirContents_.
  * @param {Function} opt_callback Called on success.
  */
 DirectoryModel.prototype.clearAndScan_ = function(newDirContents,
                                                   opt_callback) {
+  this.currentDirContents_.cancelScan();
   this.currentDirContents_ = newDirContents;
   this.clearRescanTimeout_();
 
   if (this.pendingScan_)
     this.pendingScan_ = false;
 
   if (this.runningScan_) {
     this.runningScan_.cancelScan();
     this.runningScan_ = null;
   }
@@ skipping 923 matching lines @@
         }.bind(this));
   }
 };
 
 /**
  * @return {DirectoryEntry} Current watched directory entry.
  */
 FileWatcher.prototype.getWatchedDirectoryEntry = function() {
   return this.watchedDirectoryEntry_;
 };