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

chrome/browser/signin/signin_manager_factory.cc

 // 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.
 
 #include "chrome/browser/signin/signin_manager_factory.h"
 
 #include "build/build_config.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/signin/account_fetcher_service_factory.h"
 #include "chrome/browser/signin/account_tracker_service_factory.h"
 #include "chrome/browser/signin/chrome_signin_client_factory.h"
 #include "chrome/browser/signin/gaia_cookie_manager_service_factory.h"
 #include "chrome/browser/signin/local_auth.h"
 #include "chrome/browser/signin/profile_oauth2_token_service_factory.h"
 #include "components/keyed_service/content/browser_context_dependency_manager.h"
 #include "components/prefs/pref_registry_simple.h"
+
+#if !defined(OS_ANDROID) && !defined(OS_CHROMEOS)
+#include "chrome/browser/signin/force_signin_manager.h"
+#else
 #include "components/signin/core/browser/signin_manager.h"
+#endif
 
 SigninManagerFactory::SigninManagerFactory()
     : BrowserContextKeyedServiceFactory(
         "SigninManager",
         BrowserContextDependencyManager::GetInstance()) {
   DependsOn(ChromeSigninClientFactory::GetInstance());
   DependsOn(GaiaCookieManagerServiceFactory::GetInstance());
   DependsOn(ProfileOAuth2TokenServiceFactory::GetInstance());
   DependsOn(AccountTrackerServiceFactory::GetInstance());
 }
@@ skipping 79 matching lines @@
     content::BrowserContext* context) const {
   SigninManagerBase* service = NULL;
   Profile* profile = static_cast<Profile*>(context);
   SigninClient* client =
       ChromeSigninClientFactory::GetInstance()->GetForProfile(profile);
 #if defined(OS_CHROMEOS)
   service = new SigninManagerBase(
       client,
       AccountTrackerServiceFactory::GetForProfile(profile));
 #else
-  service = new SigninManager(
-      client,
-      ProfileOAuth2TokenServiceFactory::GetForProfile(profile),
-      AccountTrackerServiceFactory::GetForProfile(profile),
-      GaiaCookieManagerServiceFactory::GetForProfile(profile));
+#if !defined(OS_ANDROID)
+  if (ForceSigninManager::IsForceSigninEnabled())
+    service = new ForceSigninManager(
+        profile, client,
+        ProfileOAuth2TokenServiceFactory::GetForProfile(profile),
+        AccountTrackerServiceFactory::GetForProfile(profile),
+        GaiaCookieManagerServiceFactory::GetForProfile(profile));
+  else
+#endif
+    service = new SigninManager(
+        client, ProfileOAuth2TokenServiceFactory::GetForProfile(profile),
+        AccountTrackerServiceFactory::GetForProfile(profile),
+        GaiaCookieManagerServiceFactory::GetForProfile(profile));

[Roger Tawa OOO till Jul 10th, 2016/10/26 18:25:31]

Nit: add { and } around if and else blocks.

   AccountFetcherServiceFactory::GetForProfile(profile);
 #endif
   service->Initialize(g_browser_process->local_state());
   for (Observer& observer : observer_list_)
     observer.SigninManagerCreated(service);
   return service;
 }
 
 void SigninManagerFactory::BrowserContextShutdown(
     content::BrowserContext* context) {
   SigninManagerBase* manager = static_cast<SigninManagerBase*>(
       GetServiceForBrowserContext(context, false));
   if (manager) {
     for (Observer& observer : observer_list_)
       observer.SigninManagerShutdown(manager);
   }
   BrowserContextKeyedServiceFactory::BrowserContextShutdown(context);
 }