cros: Move LockWindow from chrome to ash

ash/login/ui/lock_contents_view.h

 // Copyright 2017 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_LOGIN_UI_CONTENTS_VIEW_H_
 #define ASH_LOGIN_UI_CONTENTS_VIEW_H_
 
+#include "ash/ash_export.h"
 #include "base/macros.h"
 #include "ui/views/controls/button/md_text_button.h"
 #include "ui/views/view.h"
 
 namespace ash {
 
 // LockContentsView hosts the root view for the lock screen. All other lock
 // screen views are embedded within this one. LockContentsView is per-display,
 // but the lock screen should only ever be shown on a single display, so there
 // is effectively only a single instance.
-class LockContentsView : public views::View, public views::ButtonListener {
+class ASH_EXPORT LockContentsView : public views::View,
+                                    public views::ButtonListener {
  public:
   LockContentsView();
   ~LockContentsView() override;
 
   // views::ButtonListener:
   void ButtonPressed(views::Button* sender, const ui::Event& event) override;
 
  private:
   views::Button* unlock_button_;
 
   DISALLOW_COPY_AND_ASSIGN(LockContentsView);
 };
 
 }  // namespace ash
 
 #endif  // ASH_LOGIN_UI_CONTENTS_VIEW_H_