Adds AppListDelegate to AppList that is notified on visibility changes

ui/app_list/presenter/app_list_presenter_impl.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 UI_APP_LIST_PRESENTER_APP_LIST_PRESENTER_IMPL_H_
 #define UI_APP_LIST_PRESENTER_APP_LIST_PRESENTER_IMPL_H_
 
+#include <stdint.h>
+
 #include <memory>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "ui/app_list/pagination_model_observer.h"
 #include "ui/app_list/presenter/app_list_presenter.mojom.h"
 #include "ui/app_list/presenter/app_list_presenter_delegate.h"
 #include "ui/app_list/presenter/app_list_presenter_export.h"
 #include "ui/aura/client/focus_change_observer.h"
 #include "ui/aura/window_observer.h"
@@ skipping 59 matching lines @@
 
   // Sets the app list view and attempts to show it.
   void SetView(AppListView* view);
 
   // Forgets the view.
   void ResetView();
 
   // Starts show/hide animation.
   void ScheduleAnimation();
 
+  // Returns the id of the display containing the app list, if visible. If not
+  // visible returns kInvalidDisplayId.
+  int64_t GetDisplayId();
+
   // aura::client::FocusChangeObserver overrides:
   void OnWindowFocused(aura::Window* gained_focus,
                        aura::Window* lost_focus) override;
 
   // aura::WindowObserver overrides:
   void OnWindowBoundsChanged(aura::Window* root,
                              const gfx::Rect& old_bounds,
                              const gfx::Rect& new_bounds) override;
 
   // ui::ImplicitAnimationObserver overrides:
@@ skipping 33 matching lines @@
 
   // The app list interface pointer; used for reporting visibility changes.
   mojom::AppListPtr app_list_;
 
   DISALLOW_COPY_AND_ASSIGN(AppListPresenterImpl);
 };
 
 }  // namespace app_list
 
 #endif  // UI_APP_LIST_PRESENTER_APP_LIST_PRESENTER_IMPL_H_