Revert of Refactor backdrop

ash/wm/maximize_mode/workspace_backdrop_delegate.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.
+
+#ifndef ASH_WM_MAXIMIZE_MODE_WORKSPACE_BACKDROP_DELEGATE_H_
+#define ASH_WM_MAXIMIZE_MODE_WORKSPACE_BACKDROP_DELEGATE_H_
+
+#include <memory>
+
+#include "ash/ash_export.h"
+#include "ash/wm/workspace/workspace_layout_manager_backdrop_delegate.h"
+#include "base/macros.h"
+
+namespace views {
+class Widget;
+}
+
+namespace ash {
+
+class WmWindow;
+
+// A background which gets created for a container |window| and which gets
+// stacked behind the topmost window (within that container) covering the
+// entire container.
+class ASH_EXPORT WorkspaceBackdropDelegate
+    : public WorkspaceLayoutManagerBackdropDelegate {
+ public:
+  explicit WorkspaceBackdropDelegate(WmWindow* container);
+  ~WorkspaceBackdropDelegate() override;
+
+  // WorkspaceLayoutManagerBackdropDelegate overrides:
+  void OnWindowAddedToLayout(WmWindow* child) override;
+  void OnWindowRemovedFromLayout(WmWindow* child) override;
+  void OnChildWindowVisibilityChanged(WmWindow* child, bool visible) override;
+  void OnWindowStackingChanged(WmWindow* window) override;
+  void OnPostWindowStateTypeChange(wm::WindowState* window_state,
+                                   wm::WindowStateType old_type) override;
+
+ private:
+  // Restack the backdrop relatively to the other windows in the container.
+  void RestackBackdrop();
+
+  // Returns the current visible top level window in the container.
+  WmWindow* GetCurrentTopWindow();
+
+  // Show the overlay.
+  void Show();
+
+  // The background which covers the rest of the screen.
+  views::Widget* background_ = nullptr;
+  // WmWindow for |background_|.
+  WmWindow* background_window_ = nullptr;
+
+  // The window which is being "maximized".
+  WmWindow* container_;
+
+  // If true, the |RestackOrHideWindow| might recurse.
+  bool in_restacking_;
+
+  DISALLOW_COPY_AND_ASSIGN(WorkspaceBackdropDelegate);
+};
+
+}  // namespace ash
+
+#endif  // ASH_WM_MAXIMIZE_MODE_WORKSPACE_BACKDROP_DELEGATE_H_