[FileManager] Do drive search incrementally

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 1151 matching lines @@
       this.clearAndScan_(newDirContents);
       this.clearSearch_();
     }
     return;
   }
 
   // If we already have event listener for an old search, we have to remove it.
   if (this.onSearchCompleted_)
     this.removeEventListener('scan-completed', this.onSearchCompleted_);
 
+  // Current search will be cancelled.
+  if (this.onClearSearch_)
+    this.onClearSearch_();
+
   this.onSearchCompleted_ = onSearchRescan;
   this.onClearSearch_ = onClearSearch;
 
   this.addEventListener('scan-completed', this.onSearchCompleted_);
 
   // If we are offline, let's fallback to file name search inside dir.
   if (this.getCurrentRootType() === RootType.GDATA && !this.isOffline()) {
     newDirContents = new DirectoryContentsGDataSearch(
         this.currentFileListContext_, this.getCurrentDirEntry(), query);
   } else {
@@ skipping 158 matching lines @@
         }.bind(this));
   }
 };
 
 /**
  * @return {DirectoryEntry} Current watched directory entry.
  */
 FileWatcher.prototype.getWatchedDirectoryEntry = function() {
   return this.watchedDirectoryEntry_;
 };