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

components/signin/core/browser/signin_manager.h

 // Copyright 2014 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.
 //
 // The signin manager encapsulates some functionality tracking
 // which user is signed in. See SigninManagerBase for full description of
 // responsibilities. The class defined in this file provides functionality
 // required by all platforms except Chrome OS.
 //
 // When a user is signed in, a ClientLogin request is run on their behalf.
@@ skipping 129 matching lines @@
   void ProhibitSignout(bool prohibit_signout);
 
   // If true, signout is prohibited for this profile (calls to SignOut() are
   // ignored).
   bool IsSignoutProhibited() const;
 
  protected:
   // Flag saying whether signing out is allowed.
   bool prohibit_signout_;
 
+  // The sign out process which is started by SigninClient::PreSignOut()
+  virtual void DoSignOut(signin_metrics::ProfileSignout signout_source_metric,
+                         signin_metrics::SignoutDelete signout_delete_metric);
+
  private:
   enum SigninType { SIGNIN_TYPE_NONE, SIGNIN_TYPE_WITH_REFRESH_TOKEN };
 
   std::string SigninTypeToString(SigninType type);
   friend class FakeSigninManager;
   FRIEND_TEST_ALL_PREFIXES(SigninManagerTest, ClearTransientSigninData);
   FRIEND_TEST_ALL_PREFIXES(SigninManagerTest, ProvideSecondFactorSuccess);
   FRIEND_TEST_ALL_PREFIXES(SigninManagerTest, ProvideSecondFactorFailure);
 
   // If user was signed in, load tokens from DB if available.
@@ skipping 77 matching lines @@
   bool user_info_fetched_by_account_tracker_;
 
   base::WeakPtrFactory<SigninManager> weak_pointer_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(SigninManager);
 };
 
 #endif  // !defined(OS_CHROMEOS)
 
 #endif  // COMPONENTS_SIGNIN_CORE_BROWSER_SIGNIN_MANAGER_H_