MD Settings: Change search engine add button to a paper-button

chrome/browser/resources/settings/site_settings/site_list.html

 <link rel="import" href="chrome://resources/cr_elements/cr_action_menu/cr_action_menu.html">
 <link rel="import" href="chrome://resources/cr_elements/icons.html">
 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/html/web_ui_listener_behavior.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-icon-button/paper-icon-button.html">
 <link rel="import" href="../i18n_setup.html">
 <link rel="import" href="../icons.html">
 <link rel="import" href="../route.html">
 <link rel="import" href="../settings_shared_css.html">
 <link rel="import" href="add_site_dialog.html">
 <link rel="import" href="constants.html">
 <link rel="import" href="site_settings_behavior.html">
 <link rel="import" href="site_settings_prefs_browser_proxy.html">
 
 <dom-module id="site-list">
   <template>
     <style include="settings-shared">
-      paper-button {
-        margin-top: 12px;  /* Align with <h2>. */
-      }
-
       paper-icon-button {
         left: 8px;
         right: 8px;
       }
 
       .selectable {
         -webkit-user-select: text;
       }
     </style>
     <div id="category">
       <div class="settings-box first" hidden$="[[allSites]]">
         <h2 class="start">[[categoryHeader]]</h2>
-        <paper-button class="secondary-button" id="icon" on-tap="onAddSiteTap_">
+        <paper-button class="secondary-button header-aligned-button" id="icon"
+            on-tap="onAddSiteTap_">
           $i18n{add}
         </paper-button>
       </div>
 
       <dialog is="cr-action-menu">
         <button class="dropdown-item" role="option" id="allow"
             on-tap="onAllowTap_" hidden$="[[!showAllowAction_]]">
           $i18n{siteSettingsActionAllow}
         </button>
         <button class="dropdown-item" role="option" id="block"
@@ skipping 45 matching lines @@
                 </button>
               </div>
             </template>
           </div>
         </template>
       </div>
     </div>
   </template>
   <script src="site_list.js"></script>
 </dom-module>