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

chrome/browser/resources/settings/route.js

Index: chrome/browser/resources/settings/route.js
diff --git a/chrome/browser/resources/settings/route.js b/chrome/browser/resources/settings/route.js
index a8bb749454d4a28f21bf5da618ec7e5ff77d0bba..e988f8ef25de849246af1b6a9d8566478f11c732 100644
--- a/chrome/browser/resources/settings/route.js
+++ b/chrome/browser/resources/settings/route.js
@@ -334,16 +334,23 @@ cr.define('settings', function() {
   };
 
   /**
-   * 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.
+   * Return true if the previous route exsited in the history and has an equal
+   * or lesser depth. Otherwise, return false.
    */
-  var navigateToPreviousRoute = function() {
+  var isPreviousRouteExistedInHistory = function() {
     var previousRoute =
         window.history.state &&
         assert(getRouteForPath(/** @type {string} */ (window.history.state)));
+    return previousRoute && previousRoute.depth <= currentRoute_.depth;
+  };
 
-    if (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() {
+    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);
@@ -364,6 +371,7 @@ cr.define('settings', function() {
     getQueryParameters: getQueryParameters,
     lastRouteChangeWasPopstate: lastRouteChangeWasPopstate,
     navigateTo: navigateTo,
+    isPreviousRouteExistedInHistory: isPreviousRouteExistedInHistory,
     navigateToPreviousRoute: navigateToPreviousRoute,
   };
 });