Add search hint bubbles to Print Preview advanced options controls.

chrome/browser/resources/print_preview/common/search_box.js

 // Copyright 2014 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('print_preview', function() {
   'use strict';
 
   /**
    * Component that renders a search box for searching through destinations.
    * @param {string} searchBoxPlaceholderText Search box placeholder text.
@@ skipping 81 matching lines @@
 
     /**
      * Dispatches a SEARCH event.
      * @private
      */
     dispatchSearchEvent_: function() {
       this.timeout_ = null;
       var searchEvent = new Event(SearchBox.EventType.SEARCH);
       var query = this.getQuery_();
       searchEvent.query = query;
-      // Generate regexp-safe query by escaping metacharacters.
-      var safeQuery = query.replace(/[-[\]{}()*+?.,\\^$|#\s]/g, '\\$&');
-      searchEvent.queryRegExp = new RegExp('(' + safeQuery + ')', 'ig');
+      if (query) {
+        // Generate regexp-safe query by escaping metacharacters.
+        var safeQuery = query.replace(/[-[\]{}()*+?.,\\^$|#\s]/g, '\\$&');
+        searchEvent.queryRegExp = new RegExp('(' + safeQuery + ')', 'ig');
+      } else {
+        searchEvent.queryRegExp = null;
+      }
       this.dispatchEvent(searchEvent);
     },
 
     /**
      * Called when the input element's value changes. Dispatches a search event.
      * @private
      */
     onInputInput_: function() {
       if (this.timeout_)
         clearTimeout(this.timeout_);
       this.timeout_ = setTimeout(
           this.dispatchSearchEvent_.bind(this), SearchBox.SEARCH_DELAY_);
     }
   };
 
   // Export
   return {
     SearchBox: SearchBox
   };
 });