MD Webui: Improve accessibility of toolbar search field

ui/webui/resources/cr_elements/cr_toolbar/cr_toolbar_search_field.js

Index: ui/webui/resources/cr_elements/cr_toolbar/cr_toolbar_search_field.js
diff --git a/ui/webui/resources/cr_elements/cr_toolbar/cr_toolbar_search_field.js b/ui/webui/resources/cr_elements/cr_toolbar/cr_toolbar_search_field.js
index 6ebc105e84bca5c392fc6f530b257671deaa863d..4c2c3cb5b391bd2debf8a0e50773467b4f83cc4d 100644
--- a/ui/webui/resources/cr_elements/cr_toolbar/cr_toolbar_search_field.js
+++ b/ui/webui/resources/cr_elements/cr_toolbar/cr_toolbar_search_field.js
@@ -81,6 +81,15 @@ Polymer({
   },
 
   /**
+   * @param {boolean} narrow
+   * @return {string}
+   * @private
+   */
+  computeIconAriaHidden_: function(narrow) {
+    return narrow ? 'false' : 'true';

[dpapad, 2017/03/20 18:07:18]

Nit (optional): Equivalent to
return Boolean(narrow).toString();

[tsergeant, 2017/03/20 23:22:02]

Done, with an extra ! in there:

return Boolean(!narrow).toString()

+  },
+
+  /**
    * @return {boolean}
    * @private
    */