ChromeOS: user whitelist check should happen before entering password.

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

Index: chrome/browser/resources/chromeos/login/screen_gaia_signin.js
diff --git a/chrome/browser/resources/chromeos/login/screen_gaia_signin.js b/chrome/browser/resources/chromeos/login/screen_gaia_signin.js
index 8ba71345d0bfd4e807763bd5494ff06aba5188ad..b40ea23e19ccc026caf85ed80c66f55a76febae7 100644
--- a/chrome/browser/resources/chromeos/login/screen_gaia_signin.js
+++ b/chrome/browser/resources/chromeos/login/screen_gaia_signin.js
@@ -170,6 +170,8 @@ login.createScreen('GaiaSigninScreen', 'gaia-signin', function() {
           this.onAuthCompletedMessage_.bind(this));
       this.gaiaAuthHost_.addEventListener('loadAbort',
         this.onLoadAbortMessage_.bind(this));
+      this.gaiaAuthHost_.addEventListener(
+          'identifierEntered', this.onIdentifierEnteredMessage_.bind(this));
 
       $('enterprise-info-hint-link').addEventListener('click', function(e) {
         chrome.send('launchHelpApp', [HELP_TOPIC_ENTERPRISE_REPORTING]);
@@ -771,6 +773,15 @@ login.createScreen('GaiaSigninScreen', 'gaia-signin', function() {
     },
 
     /**
+     * Invoked when identifierEntered message received.
+     * @param {!Object} e Payload of the received HTML5 message.
+     * @private
+     */
+    onIdentifierEnteredMessage_: function(e) {
+      this.onIdentifierEntered(e.detail);
+    },
+
+    /**
      * Clears input fields and switches to input mode.
      * @param {boolean} takeFocus True to take focus.
      * @param {boolean} forceOnline Whether online sign-in should be forced.
@@ -905,6 +916,15 @@ login.createScreen('GaiaSigninScreen', 'gaia-signin', function() {
     },
 
     /**
+     * Handler for identifierEntered event.
+     * @param {!Object} data The identifier entered by user:
+     * {string} accountIdentifier User identifier.
+     */
+    onIdentifierEntered: function(data) {
+      chrome.send('identifierEntered', [data.accountIdentifier]);
+    },
+
+    /**
      * Sets welcome and enterpriseinfo strings for offline gaia.
      * Also sets callback and sends message whether we already have email and
      * should switch to the password screen with error.