[MD settings] make About menu item blue when selected

chrome/browser/resources/settings/settings_menu/settings_menu.html

 <link rel="import" href="chrome://resources/cr_elements/icons.html">
 <link rel="import" href="chrome://resources/html/assert.html">
 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icon/iron-icon.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-menu/paper-menu.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-menu/paper-submenu.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-ripple/paper-ripple.html">
 <link rel="import" href="/icons.html">
 <link rel="import" href="/route.html">
 <link rel="import" href="/settings_shared_css.html">
 
 <dom-module id="settings-menu">
   <template>
     <style include="settings-shared">
+      #about-menu[about-selected] {
+        color: var(--google-blue-500);
+      }
+
       iron-icon {
         --iron-icon-fill-color: var(--settings-nav-grey);
         -webkit-margin-end: 24px;
       }
 
       .iron-selected:not(.menu-trigger) > iron-icon {
         fill: var(--google-blue-500);
       }
 
       .menu-trigger span {
@@ skipping 160 matching lines @@
 </if>
           <div data-path="/reset" on-tap="openPage_"
               hidden="[[!pageVisibility.reset]]">
             <iron-icon icon="settings:restore"></iron-icon>
             $i18n{resetPageTitle}
           </div>
         </paper-menu>
       </paper-submenu>
       <div class="separator"></div>
       <paper-submenu class="page-menu">
-        <div class="menu-trigger" on-tap="openPage_" data-path="/help">
+        <div about-selected$="[[aboutSelected_]]" class="menu-trigger"
+            id="about-menu" on-tap="openPage_" data-path="/help">
           $i18n{aboutPageTitle}
         </div>
       </paper-submenu>
     </paper-menu>
   </template>
   <script src="settings_menu.js"></script>
 </dom-module>