ChromeOS: GAIA screen should support API v2.

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

 /* Copyright (c) 2012 The Chromium Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file. */
 
 #gaia-signin {
   height: 528px;
   width: 448px;
 }
 
 #gaia-signin.full-width {
   padding: 44px 0 0;
   width: 562px;
 }
 
+#gaia-signin.v2 {
+  height: unset;
+  padding: unset;
+  width: unset;
+}
+
 .signin-link {
   color: rgb(37, 79, 155);
   cursor: pointer;
   text-decoration: none;
 }
 
 .signin-link:focus {
   /* Note: May use 1px solid here. */
   outline-color: rgb(77, 144, 254);
   transition: outline-color 200ms;
@@ skipping 11 matching lines @@
   opacity: 0;
   overflow: hidden;
   transition: opacity 500ms ease-in;
 }
 
 #signin-frame.show {
   opacity: 1;
   transition: opacity 500ms ease-out;
 }
 
+#signin-frame-container-v2 #signin-frame {
+  height: 560px;
+  position: static;
+  width: 768px;
+}
+
 #gaia-signin .step-contents {
   -webkit-box-pack: center;
   display: -webkit-box;
   height: 100%;
 }
 
 #saml-notice-container {
   align-items: center;
   box-shadow: 0 2px 2px 0 rgba(0, 0, 0, 0.17);
   display: flex;
@@ skipping 44 matching lines @@
   right: 0;
   top: 0;
   z-index: 1;
 }
 
 .loading #gaia-navigation,
 .full-width #gaia-navigation {
   color: rgba(0, 0, 0, .54);
 }
 
+#gaia-signin.v2 #gaia-navigation,
+#gaia-signin.v2 #gaia-step-contents {
+  display: none;
+}
+
+#gaia-signin:not(.v2) #signin-frame-dialog {
+  display: none;
+}