cros: Move LockWindow from chrome to ash

ash/login/ui/lock_contents_view.h

Index: ash/login/ui/lock_contents_view.h
diff --git a/ash/login/ui/lock_contents_view.h b/ash/login/ui/lock_contents_view.h
index 09de518a58114cf3c2329d0b4840cf1f3e527a0f..f1d8271c7d32fa584b5bb5fcb070fb58d788a8c7 100644
--- a/ash/login/ui/lock_contents_view.h
+++ b/ash/login/ui/lock_contents_view.h
@@ -5,6 +5,7 @@
 #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"
@@ -15,7 +16,8 @@ namespace ash {
 // 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;