DevTools: Show a list of availble QuickOpen providers

third_party/WebKit/Source/devtools/front_end/quick_open/QuickOpen.js

 // Copyright 2016 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.
 
 QuickOpen.QuickOpen = class {
   constructor() {
     this._prefix = null;
     this._query = '';
     /** @type {!Map<string, function():!Promise<!QuickOpen.FilteredListWidget.Provider>>} */
     this._providers = new Map();
     /** @type {!Array<string>} */
     this._prefixes = [];
     this._filteredListWidget = null;
     self.runtime.extensions(QuickOpen.FilteredListWidget.Provider).forEach(this._addProvider.bind(this));
     this._prefixes.sort((a, b) => b.length - a.length);
   }
 
   /**
    * @param {string} query
    */
   static show(query) {
     var quickOpen = new this();
     var filteredListWidget =
         new QuickOpen.FilteredListWidget(null, this._history, quickOpen._queryChanged.bind(quickOpen));
     quickOpen._filteredListWidget = filteredListWidget;
+    filteredListWidget.setPlaceholder(Common.UIString('Type \'?\' to see available commands'));
     filteredListWidget.showAsDialog();
     filteredListWidget.setQuery(query);
   }
 
   /**
    * @param {!Runtime.Extension} extension
    */
   _addProvider(extension) {
     var prefix = extension.descriptor()['prefix'];
     this._prefixes.push(prefix);
@@ skipping 42 matching lines @@
    */
   handleAction(context, actionId) {
     switch (actionId) {
       case 'quickOpen.show':
         QuickOpen.QuickOpen.show('');
         return true;
     }
     return false;
   }
 };