Re-reland: chromeos: Fix shelf appearing at login screen under mash

ash/mus/test/wm_test_base.h

 // 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.
 
 #ifndef ASH_MUS_TEST_WM_TEST_BASE_H_
 #define ASH_MUS_TEST_WM_TEST_BASE_H_
 
 #include <memory>
 #include <string>
 
@@ skipping 64 matching lines @@
                                       const gfx::Rect& bounds);
 
  protected:
   // testing::Test:
   void SetUp() override;
   void TearDown() override;
 
  private:
   friend class AshTestImplMus;
 
+  // Simulates the first user logging in and the session becoming active.
+  // Classic ash handles this via AshTestHelper and TestSessionStateDelegate.
+  void SimulateUserLogin();
+
   bool setup_called_ = false;
   bool teardown_called_ = false;
   std::unique_ptr<ui::ScopedAnimationDurationScaleMode> zero_duration_mode_;
   std::unique_ptr<WmWindowAuraTestApi::GlobalMinimumSizeLock>
       minimum_size_lock_;
   std::unique_ptr<WmTestHelper> test_helper_;
 
   DISALLOW_COPY_AND_ASSIGN(WmTestBase);
 };
 
 }  // namespace mus
 }  // namespace ash
 
 #endif  // ASH_MUS_TEST_WM_TEST_BASE_H_