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

chrome/browser/resources/settings/route.js

 // Copyright 2016 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.
 
 cr.define('settings', function() {
   /**
    * Class for navigable routes. May only be instantiated within this file.
    * @constructor
    * @param {string} path
    * @private
@@ skipping 316 matching lines @@
       if (queryString)
         url += '?' + queryString;
     }
 
     // History serializes the state, so we don't push the actual route object.
     window.history.pushState(currentRoute_.path, '', url);
     setCurrentRoute(route, params, false);
   };
 
   /**
+   * Return true if the previous route exsited in the history and has an equal
+   * or lesser depth. Otherwise, return false.
+   */
+  var isPreviousRouteExistedInHistory = function() {
+    var previousRoute =
+        window.history.state &&
+        assert(getRouteForPath(/** @type {string} */ (window.history.state)));
+    return previousRoute && previousRoute.depth <= currentRoute_.depth;
+  };
+
+  /**
    * Navigates to the previous route if it has an equal or lesser depth.
    * If there is no previous route in history meeting those requirements,
    * this navigates to the immediate parent. This will never exit Settings.
    */
   var navigateToPreviousRoute = function() {
-    var previousRoute =
-        window.history.state &&
-        assert(getRouteForPath(/** @type {string} */ (window.history.state)));
-
-    if (previousRoute && previousRoute.depth <= currentRoute_.depth)
+    if (isPreviousRouteExistedInHistory())

[tommycli, 2016/11/02 18:46:57]

I'm sorry - but I just don't think this is a good idea --

The core idea of the CL is that we need to remove chrome://settings/signOut from
the Session Restore list after a Force signout.

With these changes, it's not obvious how this is accomplished - future
developers would have to disentangle how the navigable dialog interacts with the
routing.

I think it would be much better to discard chrome://settings/signOut from the
list of Session Restored URLs - or redirect to chrome://settings

At least - we should give an effort to investigate how complicated that is. I
think the above would be much simpler.

There is already precedent in the Session Restore code for treating internal
URLs differently:
https://cs.chromium.org/chromium/src/chrome/browser/sessions/session_restore_...

       window.history.back();
     else
       navigateTo(currentRoute_.parent || Route.BASIC);
   };
 
   window.addEventListener('popstate', function(event) {
     // On pop state, do not push the state onto the window.history again.
     setCurrentRoute(getRouteForPath(window.location.pathname) || Route.BASIC,
                     new URLSearchParams(window.location.search), true);
   });
 
   return {
     Route: Route,
     RouteObserverBehavior: RouteObserverBehavior,
     getRouteForPath: getRouteForPath,
     initializeRouteFromUrl: initializeRouteFromUrl,
     getCurrentRoute: getCurrentRoute,
     getQueryParameters: getQueryParameters,
     lastRouteChangeWasPopstate: lastRouteChangeWasPopstate,
     navigateTo: navigateTo,
+    isPreviousRouteExistedInHistory: isPreviousRouteExistedInHistory,
     navigateToPreviousRoute: navigateToPreviousRoute,
   };
 });