[MD settings] using h2 for sub-headers consistently.

chrome/browser/resources/settings/passwords_and_forms_page/autofill_section.html

 <link rel="import" href="chrome://resources/cr_elements/cr_shared_menu/cr_shared_menu.html">
 <link rel="import" href="chrome://resources/html/action_link.html">
 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-icon-button/paper-icon-button.html">
 <link rel="import" href="/passwords_and_forms_page/address_edit_dialog.html">
 <link rel="import" href="/passwords_and_forms_page/credit_card_edit_dialog.html">
 <link rel="import" href="/passwords_and_forms_page/passwords_shared_css.html">
 <link rel="import" href="/settings_shared_css.html">
 
 <dom-module id="settings-autofill-section">
   <link rel="import" type="css" href="chrome://resources/css/action_link.css">
   <template>
     <style include="settings-shared passwords-shared">
-      .link-item {
-        border-top: var(--settings-separator-line);
-      }
-
       .menu-item {
         @apply(--settings-actionable);
       }
 
       .type-column {
         align-items: center;
         flex: 2;
       }
 
       .expiration-column {
         align-items: center;
         display: flex;
         flex: 1;
       }
 
       .expiration-date {
         flex: 1;
       }
 
       .payments-label {
         -webkit-margin-start: 16px;
         color: var(--paper-grey-600);
       }
     </style>
-    <div class="heading">$i18n{addresses}</div>
-    <div class="item-list">
-      <div id="addressList" class="vertical-list list-section">
+    <div class="settings-box first">
+      <h2>$i18n{addresses}</h2>
+    </div>
+    <div class="list-frame">
+      <div id="addressList" class="vertical-list">
         <template is="dom-repeat" items="[[addresses]]">
           <div class="list-item two-line">
             <div class="start">
               <span id="addressSummary">[[address_(item)]]</span>
               <span class="payments-label" hidden$="[[item.metadata.isLocal]]">
                 $i18n{googlePayments}
               </span>
             </div>
             <paper-icon-button id="addressMenu" icon="cr:more-vert"
                 tabindex$="[[tabIndex]]" alt="$i18n{overflowMenu}"
                 on-tap="onAddressMenuTap_">
             </paper-icon-button>
           </div>
         </template>
       </div>
-      <div class="list-item link-item">
+      <div class="list-item list-button">
         <a is="action-link" on-tap="onAddAddressTap_">$i18n{addAddress}</a>
       </div>
     </div>
     <cr-shared-menu id="addressSharedMenu">
       <button id="menuEditAddress" class="list-item menu-item"
           on-tap="onMenuEditAddressTap_">$i18n{editAddress}</button>
       <button id="menuRemoveAddress" class="list-item menu-item"
           on-tap="onMenuRemoveAddressTap_">$i18n{removeAddress}</button>
     </cr-shared-menu>
     <template is="dom-if" if="[[activeAddress]]" restamp>
       <settings-address-edit-dialog address="[[activeAddress]]"
           on-close="unstampAddressEditDialog_">
       </settings-address-edit-dialog>
     </template>
-    <div class="heading">$i18n{creditCards}</div>
-    <div class="item-list">
+    <div class="settings-box first">
+      <h2>$i18n{creditCards}</h2>
+    </div>
+    <div class="list-frame">
       <div class="list-item column-header">
         <div class="type-column">$i18n{creditCardType}</div>
         <div class="expiration-column">$i18n{creditCardExpiration}</div>
       </div>
-      <div id="creditCardList"
-          class="vertical-list list-section list-with-header">
+      <div id="creditCardList" class="vertical-list list-with-header">
         <template is="dom-repeat" items="[[creditCards]]">
           <div class="list-item two-line">
             <div class="type-column">
               <span id="creditCardLabel">[[item.metadata.summaryLabel]]</span>
               <span class="payments-label" hidden$="[[item.metadata.isLocal]]">
                 <span hidden$="[[item.metadata.isCached]]">
                   $i18n{googlePayments}
                 </span>
                 <span hidden$="[[!item.metadata.isCached]]">
                   $i18n{googlePaymentsCached}
                 </span>
               </span>
             </div>
             <div class="expiration-column">
               <div id="creditCardExpiration"
                   class="expiration-date">[[expiration_(item)]]</div>
               <paper-icon-button id="creditCardMenu" icon="cr:more-vert"
                   tabindex$="[[tabIndex]]" alt="$i18n{overflowMenu}"
                   on-tap="onCreditCardMenuTap_">
               </paper-icon-button>
             </div>
           </div>
         </template>
       </div>
-      <div class="list-item link-item">
+      <div class="list-item list-button">
         <a is="action-link" on-tap="onAddCreditCardTap_">
           $i18n{addCreditCard}
         </a>
       </div>
     </div>
     <cr-shared-menu id="creditCardSharedMenu">
       <button id="menuEditCreditCard" class="list-item menu-item"
           on-tap="onMenuEditCreditCardTap_">$i18n{editCreditCard}</button>
       <button id="menuRemoveCreditCard" class="list-item menu-item"
           on-tap="onMenuRemoveCreditCardTap_">$i18n{removeCreditCard}</button>
       <button id="menuClearCreditCard" class="list-item menu-item"
           on-tap="onMenuClearCreditCardTap_">$i18n{clearCreditCard}</button>
     </cr-shared-menu>
     <template is="dom-if" if="[[activeCreditCard]]" restamp>
       <settings-credit-card-edit-dialog credit-card="[[activeCreditCard]]"
           on-close="unstampCreditCardEditDialog_">
       </settings-credit-card-edit-dialog>
     </template>
   </template>
   <script src="/passwords_and_forms_page/autofill_section.js"></script>
 </dom-module>