MD WebUI: Ensure the search field opens on touchscreen tap

ui/webui/resources/cr_elements/cr_toolbar/cr_toolbar_search_field.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.
 
 // TODO(tsergeant): Add tests for cr-toolbar-search-field.
 Polymer({
   is: 'cr-toolbar-search-field',
 
   behaviors: [CrSearchFieldBehavior],
 
@@ skipping 29 matching lines @@
     },
 
     /** @private */
     searchFocused_: {
       type: Boolean,
       value: false
     },
   },
 
   listeners: {
-    'tap': 'showSearch_',
+    // Deliberately uses 'click' instead of 'tap' to fix crbug.com/624356.
+    'click': 'showSearch_',
   },
 
   /** @return {!HTMLInputElement} */
   getSearchInput: function() {
     return this.$.searchInput;
   },
 
   /**
    * Sets the value of the search field. Overridden from CrSearchFieldBehavior.
    * @param {string} value
@@ skipping 63 matching lines @@
 
   /**
    * @param {Event} e
    * @private
    */
   clearSearch_: function(e) {
     this.setValue('');
     this.getSearchInput().focus();
   }
 });