Using WmDisplayObserver in ScreenPinningController.

ash/wm/screen_pinning_controller.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_WM_SCREEN_PINNING_CONTROLLER_H_
 #define ASH_WM_SCREEN_PINNING_CONTROLLER_H_
 
 #include <memory>
 #include <vector>
 
-#include "ash/display/window_tree_host_manager.h"
+#include "ash/common/wm_display_observer.h"
 #include "base/macros.h"
 
 namespace aura {
 class Window;
 }
 
 namespace ash {
 
 class WindowDimmer;
-class WindowTreeHostManager;
 class WmWindow;
 
 template <typename UserData>
 class WindowUserData;
 
 // Supports "screen pinning" for ARC++ apps. From the Android docs:
 // "Lets you temporarily restrict users from leaving your task or being
 // interrupted by notifications. This could be used, for example, if you are
 // developing an education app to support high stakes assessment requirements on
 // Android, or a single-purpose or kiosk application."
 // https://developer.android.com/about/versions/android-5.0.html#ScreenPinning
 // See also ArcKioskAppLauncher::CheckAndPinWindow().
-class ScreenPinningController : public WindowTreeHostManager::Observer {
+class ScreenPinningController : public WmDisplayObserver {
  public:
-  explicit ScreenPinningController(
-      WindowTreeHostManager* window_tree_host_manager);
+  ScreenPinningController();
   ~ScreenPinningController() override;
 
   // Sets a pinned window. It is not allowed to call this when there already
   // is a pinned window.
   void SetPinnedWindow(WmWindow* pinned_window);
 
   // Returns true if in pinned mode, otherwise false.
   bool IsPinned() const;
 
   // Returns the pinned window if in pinned mode, or nullptr.
@@ skipping 29 matching lines @@
   // Keeps the pinned window on top of the siblings.
   void KeepPinnedWindowOnTop();
 
   // Keeps the dim window at bottom of the container.
   void KeepDimWindowAtBottom(aura::Window* container);
 
   // Creates a WindowDimmer for |container| and places it in |window_dimmers_|.
   // Returns the window from WindowDimmer.
   WmWindow* CreateWindowDimmer(WmWindow* container);
 
-  // WindowTreeHostManager::Observer:
+  // WmDisplayObserver:
   void OnDisplayConfigurationChanged() override;
 
   // Pinned window should be on top in the parent window.
   WmWindow* pinned_window_ = nullptr;
 
   // Owns the WindowDimmers. There is one WindowDimmer for the parent of
   // |pinned_window_| and one for each display other than the display
   // |pinned_window_| is on.
   std::unique_ptr<WindowUserData<WindowDimmer>> window_dimmers_;
 
   // Set true only when restacking done by this controller.
   bool in_restacking_ = false;
 
-  // Keep references to remove this as a observer.
-  // While this controller is alive, it needs to be ensured that the instances
-  // refered from the pointers should be alive.
-  WindowTreeHostManager* window_tree_host_manager_;
-
   // Window observers to translate events for the window to this controller.
   std::unique_ptr<PinnedContainerWindowObserver>
       pinned_container_window_observer_;
   std::unique_ptr<PinnedContainerChildWindowObserver>
       pinned_container_child_window_observer_;
   std::unique_ptr<SystemModalContainerWindowObserver>
       system_modal_container_window_observer_;
   std::unique_ptr<SystemModalContainerChildWindowObserver>
       system_modal_container_child_window_observer_;
 
   DISALLOW_COPY_AND_ASSIGN(ScreenPinningController);
 };
 
 }  // namespace ash
 
 #endif  // ASH_WM_SCREEN_PINNING_CONTROLLER_H_