Reland of Clear the login webview when SAML flow is canceled

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

 // 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.
 
 /**
  * @fileoverview Oobe signin screen implementation.
  */
 
 login.createScreen('GaiaSigninScreen', 'gaia-signin', function() {
   // GAIA animation guard timer. Started when GAIA page is loaded
@@ skipping 539 matching lines @@
       $('login-header-bar').signinUIState = SIGNIN_UI_STATE.HIDDEN;
       $('offline-gaia').switchToEmailCard(false /* animated */);
     },
 
     /**
      * Loads the authentication extension into the iframe.
      * @param {Object} data Extension parameters bag.
      * @private
      */
     loadAuthExtension: function(data) {
+      // Redirect the webview to the blank page in order to stop the SAML IdP
+      // page from working in a background (see crbug.com/613245).
+      if (this.screenMode_ == ScreenMode.DEFAULT &&
+          data.screenMode != ScreenMode.DEFAULT) {
+        this.gaiaAuthHost_.resetWebview();
+      }
+
       this.screenMode = data.screenMode;
       this.email = '';
       this.authCompleted_ = false;
       this.lastBackMessageValue_ = false;
 
       $('login-header-bar').showCreateSupervisedButton =
           data.supervisedUsersCanCreate;
       $('login-header-bar').showGuestButton = data.guestSignin;
 
       // Reset SAML
@@ skipping 346 matching lines @@
     },
 
     /**
      * 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.
      * If |forceOnline| is false previously used sign-in type will be used.
      */
     reset: function(takeFocus, forceOnline) {
       // Reload and show the sign-in UI if needed.
-      this.gaiaAuthHost_.resetStates_();
+      this.gaiaAuthHost_.resetStates();
       if (takeFocus) {
         if (!forceOnline && this.isOffline()) {
           // Show 'Cancel' button to allow user to return to the main screen
           // (e.g. this makes sense when connection is back).
           Oobe.getInstance().headerHidden = false;
           $('login-header-bar').signinUIState = SIGNIN_UI_STATE.GAIA_SIGNIN;
           // Do nothing, since offline version is reloaded after an error comes.
         } else {
           Oobe.showSigninUI();
         }
@@ skipping 103 matching lines @@
       this.classList.toggle('whitelist-error', show);
       this.loading = !show;
 
       if (!show)
         Oobe.showSigninUI();
 
       this.updateControlsState();
     }
   };
 });