Override SigninManager::SignOut if force-signin is enabled.

chrome/browser/resources/settings/people_page/people_page.js

 // Copyright 2015 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
  * 'settings-people-page' is the settings page containing sign-in settings.
  */
 Polymer({
   is: 'settings-people-page',
@@ skipping 213 matching lines @@
 
   /** @private */
   onSigninTap_: function() {
     this.syncBrowserProxy_.startSignIn();
   },
 
   /** @private */
   onDisconnectClosed_: function() {
     if (settings.getCurrentRoute() == settings.Route.SIGN_OUT)
       settings.navigateToPreviousRoute();
+    window.dispatchEvent(new Event('signout-dialog-closed'));
   },
 
   /** @private */
   onDisconnectTap_: function() {
     settings.navigateTo(settings.Route.SIGN_OUT);
   },
 
   /** @private */
   onDisconnectCancel_: function() {
     this.$.disconnectDialog.close();
   },
 
   /** @private */
   onDisconnectConfirm_: function() {
     var deleteProfile = !!this.syncStatus.domain ||
         (this.$.deleteProfile && this.$.deleteProfile.checked);
-    this.syncBrowserProxy_.signOut(deleteProfile);
-
+    // Close the dialog and navigate to previous route before signout so
+    // session restore does not restore to the signout dialog.
     this.$.disconnectDialog.close();
+    // If user visit the signout dialog by typing in the address bar, there
+    // will be no previous browsing history so signout right after the dialog
+    // being closed. Otherwise, signout after the route has been navigated to
+    // the privious one with a callback.
+    var signoutEvent = 'signout-dialog-closed';
+    if (settings.isPreviousRouteExistedInHistory())
+      signoutEvent = 'popstate';
+    listenOnce(window, signoutEvent, function callback() {
+      this.syncBrowserProxy_.signOut(deleteProfile);
+    }.bind(this));
   },
 
   /** @private */
   onSyncTap_: function() {
     assert(this.syncStatus.signedIn);
     assert(this.syncStatus.syncSystemEnabled);
 
     if (this.syncStatus.managed)
       return;
 
@@ skipping 98 matching lines @@
 
   /**
    * @param {!settings.SyncStatus} syncStatus
    * @return {boolean} Whether to show the "Sign in to Chrome" button.
    * @private
    */
   showSignin_: function(syncStatus) {
     return !!syncStatus.signinAllowed && !syncStatus.signedIn;
   },
 });