Show spinner for constrained signin flow

and change the spinner background color to the same as EmbeddedSignin, otherwise user may see flicker.

BUG=385876

Review URL: https://codereview.chromium.org/335193002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@278283 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/resources/inline_login/inline_login.css

@@ -16,6 +16,7 @@ body,
 
 #signin-frame,
 #spinner-container {
+  background-color: #f5f5f5;
   bottom: 0;
   left: 0;
   position: absolute;

chrome/browser/resources/inline_login/inline_login.js

@@ -56,7 +56,8 @@ cr.define('inline.login', function() {
   function loadAuthExtension(data) {
     authExtHost.load(data.authMode, data, onAuthCompleted);
     $('contents').classList.toggle('loading',
-        data.authMode != cr.login.GaiaAuthHost.AuthMode.DESKTOP);
+        data.authMode != cr.login.GaiaAuthHost.AuthMode.DESKTOP ||
+        data.constrained == '1');
   }
 
   /**