Sync UI: Ensure the close button is shown.

chrome/browser/resources/sync_setup_overlay.html

 <div id="sync-setup-overlay" class="page" hidden>
+  <div class="close-button"></div>
   <div id="sync-setup-login" hidden>
     <div id="promo-title-container" hidden>
       <h1 i18n-content="promoTitle"></h1>
       <h2>
         <span i18n-content="promoTitleShort"></span>
         <a id="promo-learn-more" i18n-content="promoLearnMore"
             i18n-values="href:promoLearnMoreURL">
         </a>
       </h2>
     </div>
     <div class="sync-main-content">
       <div id="sync-setup-login-content-column">
-        <div class="close-button"></div>
         <h1 id="sync-setup-overlay-title" i18n-content="syncSetupOverlay"></h1>
         <div class="sign-in">
           <div id="top-blurb-error" class="reset-hidden" hidden>
             <span id="error-signing-in" i18n-content="errorSigningIn"></span>
             <span id="error-custom" hidden></span>
           </div>
           <div class="signin-box">
             <div id="signin-header">
               <h2 i18n-content="signinHeader"></h2>
               <div id="signin-header-logo"></div>
@@ skipping 122 matching lines @@
           <div class="button-strip">
             <input id="confirm-everything-cancel" type="button"
                 i18n-values="value:cancel">
             <input id="confirm-everything-ok" type="button"
                 i18n-values="value:syncEverything">
           </div>
         </div>
       </div>
     </div>
     <div id="customize-sync-preferences" hidden>
-      <div class="close-button"></div>
       <h1 i18n-content="syncSetupConfigureTitle"></h1>
       <form id="choose-data-types-form">
         <div id="sync-configure-content" class="content-area">
           <div id="sync-select-container">
             <select id="sync-select-datatypes">
               <option i18n-content="syncAllDataTypes" selected></option>
               <option i18n-content="chooseDataTypes"></option>
             </select>
             <div id="choose-data-types-body">
               <div id="apps-item" class="sync-type-checkbox checkbox">
@@ skipping 166 matching lines @@
             <input id="choose-datatypes-cancel" type="button"
                 i18n-values="value:cancel">
             <input id="choose-datatypes-ok" type="submit"
                 i18n-values="value:ok">
           </div>
         </div>
       </form>
     </div>
   </div>
   <div id="sync-setup-spinner" hidden>
-    <div class="close-button"></div>
     <h1 i18n-content="syncSetupConfigureTitle"></h1>
     <div class="content-area">
       <div id="spinner-throbber" class="throbber"></div>
     </div>
     <div class="action-area button-strip">
       <input id="sync-spinner-cancel" type="button" i18n-values="value:cancel">
     </div>
   </div>
   <div id="sync-setup-stop-syncing" hidden>
-    <div class="close-button"></div>
     <h1 i18n-content="stopSyncingTitle"></h1>
     <div class="content-area">
       <span i18n-values=".innerHTML:stopSyncingExplanation"></span>
     </div>
     <div class="action-area button-strip">
       <input id="stop-syncing-cancel" type="button"
           i18n-values="value:cancel">
       <input id="stop-syncing-ok" type="button"
           i18n-values="value:stopSyncingConfirm">
     </div>
   </div>
 </div>