ChromeOS: GAIA screen should support API v2.

chrome/browser/resources/chromeos/login/screen_gaia_signin.html

 <link rel="import" href="chrome://oobe/custom_elements.html">
 
 <div class="step right hidden no-logo" id="gaia-signin" role="group"
     aria-live="polite" hidden>
-  <div class="step-contents">
+  <link rel="stylesheet" href="oobe_dialog_parameters.css">
+  <oobe-dialog id="signin-frame-dialog" role="dialog" has-buttons no-header
+      no-footer-padding hidden>
+    <div id="signin-frame-container-v2" class="footer flex layout vertical">
+    </div>
+    <div class="bottom-buttons flex layout horizontal">
+      <oobe-back-button id="signin-back-button">
+      </oobe-back-button>
+      <div class="flex">
+      </div>
+      <oobe-next-button inverse disabled>
+      </oobe-next-button>
+    </div>
+  </oobe-dialog>
+  <div id="gaia-step-contents" class="step-contents">
     <div id="gaia-signin-form-container">
       <webview id="signin-frame" name="signin-frame" hidden></webview>
       <offline-gaia id="offline-gaia" class="fit" hidden></offline-gaia>
       <saml-interstitial id="saml-interstitial" class="fit" hidden>
       </saml-interstitial>
       <offline-ad-login id="offline-ad-auth" class="fit" hidden
           i18n-values="ad-welcome-message:adAuthWelcomeMessage">
       </offline-ad-login>
     </div>
   </div>
   <div id="gaia-loading" class="step-loading" hidden>
     <throbber-notice i18n-values="text:gaiaLoading"></throbber-notice>
   </div>
   <notification-card id="gaia-whitelist-error" type="fail"
       i18n-values="button-label:tryAgainButton;
                    link-label:learnMoreButton">
   </notification-card>
   <div id="saml-notice-container" hidden>
     <span id="saml-notice-recording-indicator" hidden>
       <img src="chrome://theme/IDR_TAB_RECORDING_INDICATOR">
     </span>
     <span id="saml-notice-message"></span>
   </div>
   <navigation-bar id="gaia-navigation"></navigation-bar>
 </div>