MD Downloads: track downloads in C++, dispatch discrete JS updates

chrome/browser/resources/md_downloads/action_service.js

 // Copyright 2015 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.
 
 cr.define('downloads', function() {
   /**
    * @param {string} chromeSendName
    * @return {function(string):void} A chrome.send() callback with curried name.
    */
   function chromeSendWithId(chromeSendName) {
     return function(id) { chrome.send(chromeSendName, [id]); };
   }
 
   /** @constructor */
   function ActionService() {}
 
+  /**
+   * @param {string} searchText Input typed by the user into a search box.
+   * @return {Array<string>} A list of terms extracted from |searchText|.
+   */
+  ActionService.splitTerms = function(searchText) {
+    /**
+     * @param {string} s
+     * @return {string} |s| without whitespace at the beginning or end.
+     */
+    function trim(s) { return s.trim(); }
+
+    /**
+     * @param {string} s
+     * @return {boolean} Whether |s| is empty.
+     */
+    function notEmpty(s) { return s.length > 0; }

[dpapad, 2015/11/25 17:50:47]

Nit: We are re-defining the trim() and notEpmty() functions every time
splitTerms() is called. How about moving the outside of splitTerms (but still
within the cr.definde('downloads', function() {...}).

[Dan Beam, 2015/11/25 20:23:23]

Done.

+
+    // Split quoted terms (e.g., 'The "lazy" dog' => ['The', 'lazy', 'dog']).
+    return searchText.split(/"([^"]*)"/).map(trim).filter(notEmpty);
+  };
+
   ActionService.prototype = {
     /** @param {string} id ID of the download to cancel. */
     cancel: chromeSendWithId('cancel'),
 
     /** Instructs the browser to clear all finished downloads. */
     clearAll: function() {
       if (loadTimeData.getBoolean('allowDeletingHistory')) {
         chrome.send('clearAll');
         this.search('');
       }
@@ skipping 11 matching lines @@
     },
 
     /** @param {string} id ID of the download that the user started dragging. */
     drag: chromeSendWithId('drag'),
 
     /**
      * @return {boolean} Whether the user is currently searching for downloads
      *     (i.e. has a non-empty search term).
      */
     isSearching: function() {
-      return this.searchText_.length > 0;
+      return !!this.searchText_;

[dpapad, 2015/11/25 17:50:47]

If you follow the comment above, then you can re-use the notEmpty() here, as
notEmpty(this.searchText_);

[Dan Beam, 2015/11/25 20:23:23]

changed a little, but basically doing this

     },
 
     /** Opens the current local destination for downloads. */
     openDownloadsFolder: chrome.send.bind(chrome, 'openDownloadsFolder'),
 
     /**
      * @param {string} id ID of the download to run locally on the user's box.
      */
     openFile: chromeSendWithId('openFile'),
 
@@ skipping 11 matching lines @@
      *     warnings.
      */
     saveDangerous: chromeSendWithId('saveDangerous'),
 
     /** @param {string} searchText What to search for. */
     search: function(searchText) {
       if (this.searchText_ == searchText)
         return;
 
       this.searchText_ = searchText;
-
-      // Split quoted terms (e.g., 'The "lazy" dog' => ['The', 'lazy', 'dog']).
-      function trim(s) { return s.trim(); }
-      chrome.send('getDownloads', searchText.split(/"([^"]*)"/).map(trim));
+      chrome.send('getDownloads', ActionService.splitTerms(searchText));
     },
 
     /**
      * Shows the local folder a finished download resides in.
      * @param {string} id ID of the download to show.
      */
     show: chromeSendWithId('show'),
 
     /** Undo download removal. */
     undo: chrome.send.bind(chrome, 'undo'),
   };
 
   cr.addSingletonGetter(ActionService);
 
   return {ActionService: ActionService};
 });