Revert "chromeos: Fix shelf appearing at login screen under mash"

chrome/browser/ui/ash/multi_user/multi_user_window_manager_stub.h

 // Copyright 2013 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.
 
 #ifndef CHROME_BROWSER_UI_ASH_MULTI_USER_MULTI_USER_WINDOW_MANAGER_STUB_H_
 #define CHROME_BROWSER_UI_ASH_MULTI_USER_MULTI_USER_WINDOW_MANAGER_STUB_H_
 
 #include <map>
 #include <string>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "chrome/browser/ui/ash/multi_user/multi_user_window_manager.h"
 
 class AccountId;
 
 namespace chrome {
 
 // This is the implementation of MultiUserWindowManager for single user mode.
 class MultiUserWindowManagerStub : public MultiUserWindowManager {
  public:
-  MultiUserWindowManagerStub();
-  ~MultiUserWindowManagerStub() override;
+  MultiUserWindowManagerStub() {}
+  ~MultiUserWindowManagerStub() override {}
 
   // MultiUserWindowManager overrides:
   void SetWindowOwner(aura::Window* window,
                       const AccountId& account_id) override;
   const AccountId& GetWindowOwner(aura::Window* window) const override;
   void ShowWindowForUser(aura::Window* window,
                          const AccountId& account_id) override;
   bool AreWindowsSharedAmongUsers() const override;
   void GetOwnersOfVisibleWindows(
       std::set<AccountId>* account_ids) const override;
   bool IsWindowOnDesktopOfUser(aura::Window* window,
                                const AccountId& account_id) const override;
   const AccountId& GetUserPresentingWindow(aura::Window* window) const override;
   void AddUser(content::BrowserContext* context) override;
   void AddObserver(Observer* observer) override;
   void RemoveObserver(Observer* observer) override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(MultiUserWindowManagerStub);
 };
 
 }  // namespace chrome
 
 #endif  // CHROME_BROWSER_UI_ASH_MULTI_USER_MULTI_USER_WINDOW_MANAGER_STUB_H_