Fix shelf auto-hide calculation for app-list visibility.

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 <memory>
 
 #include "base/compiler_specific.h"
@@ skipping 36 matching lines @@
   // Returns app list window or NULL if it is not visible.
   aura::Window* GetWindow();
 
   // Returns app list view if one exists, or NULL otherwise.
   AppListView* GetView() { return view_; }
 
   // AppListPresenter:
   void Show(int64_t display_id) override;
   void Dismiss() final;
   void ToggleAppList(int64_t display_id) override;
-  bool IsVisible() const override;
-  bool GetTargetVisibility() const override;
+  bool IsVisible(
+      int64_t display_id = display::kInvalidDisplayId) const override;
+  bool GetTargetVisibility(
+      int64_t display_id = display::kInvalidDisplayId) const override;
 
  private:
   friend class test::AppListPresenterImplTestApi;
 
   // Sets the app list view and attempts to show it.
   void SetView(AppListView* view);
 
   // Forgets the view.
   void ResetView();
 
@@ skipping 20 matching lines @@
   void SelectedPageChanged(int old_selected, int new_selected) override;
   void TransitionStarted() override;
   void TransitionChanged() override;
 
   // Not owned
   AppListPresenterDelegateFactory* const factory_;
 
   // Responsible for laying out the app list UI.
   std::unique_ptr<AppListPresenterDelegate> presenter_delegate_;
 
-  // Whether we should show or hide app list widget.
-  bool is_visible_ = false;
+  // The id of the display on which the app list should be shown. A valid id
+  // means the target visiblity is shown, while invalid means hidden.

[James Cook, 2016/11/30 23:27:20]

nit: visibility

+  int64_t target_display_id_ = display::kInvalidDisplayId;

[James Cook, 2016/11/30 23:27:19]

optional: I'd also be OK with separate target_visibility_ and target_display_id_
params if you didn't want to have to explain that invalid means hidden.

 
   // The AppListView this class manages, owned by its widget.
   AppListView* view_ = nullptr;
 
   // The current page of the AppsGridView of |view_|. This is stored outside of
   // the view's PaginationModel, so that it persists when the view is destroyed.
   int current_apps_page_ = -1;
 
   // Cached bounds of |view_| for snapping back animation after over-scroll.
   gfx::Rect view_bounds_;
 
   // Whether should schedule snap back animation.
   bool should_snap_back_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(AppListPresenterImpl);
 };
 
 }  // namespace app_list
 
 #endif  // UI_APP_LIST_PRESENTER_APP_LIST_PRESENTER_IMPL_H_