CrOS: Get rid of "IsHomeScreenAvailable"

Whether the home screen is available is strictly equivalent to whether
tablet mode is on. I understand the desire for the extra level of
indirection but it doesn't seem like this is changing anytime soon,
and if/when it does, it won't be hard to re-add :-) In the mean time,
I think we should favor readability / understandability.

Bug: 982512
Change-Id: Ifb34f316ae0fe579ee2854b70025a0b2de216d93
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1826198Reviewed-by: Alex Newcomer <newcomer@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Auto-Submit: Manu Cornet <manucornet@chromium.org>
Commit-Queue: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#700341}

ash/app_list/app_list_controller_impl.cc

@@ -64,10 +64,6 @@ namespace ash {
 
 namespace {
 
-bool IsHomeScreenAvailable() {
-  return Shell::Get()->home_screen_controller()->IsHomeScreenAvailable();
-}
-
 bool IsTabletMode() {
   return Shell::Get()->tablet_mode_controller()->InTabletMode();
 }
@@ -474,7 +470,7 @@ void AppListControllerImpl::OnAppListItemAdded(app_list::AppListItem* item) {
 
 void AppListControllerImpl::OnActiveUserPrefServiceChanged(
     PrefService* /* pref_service */) {
-  if (!IsHomeScreenAvailable()) {
+  if (!IsTabletMode()) {
     DismissAppList();
     return;
   }
@@ -552,7 +548,7 @@ void AppListControllerImpl::UpdateYPositionAndOpacity(
     int y_position_in_screen,
     float background_opacity) {
   // Avoid changing app list opacity and position when homecher is enabled.
-  if (IsHomeScreenAvailable())
+  if (IsTabletMode())
     return;
   presenter_.UpdateYPositionAndOpacity(y_position_in_screen,
                                        background_opacity);
@@ -561,7 +557,7 @@ void AppListControllerImpl::UpdateYPositionAndOpacity(
 void AppListControllerImpl::EndDragFromShelf(
     ash::AppListViewState app_list_state) {
   // Avoid dragging app list when homecher is enabled.
-  if (IsHomeScreenAvailable())
+  if (IsTabletMode())
     return;
   presenter_.EndDragFromShelf(app_list_state);
 }
@@ -590,7 +586,7 @@ ash::AppListViewState AppListControllerImpl::GetAppListViewState() {
 }
 
 void AppListControllerImpl::OnShelfAlignmentChanged(aura::Window* root_window) {
-  if (!IsHomeScreenAvailable())
+  if (!IsTabletMode())
     DismissAppList();
 }
 
@@ -601,7 +597,7 @@ void AppListControllerImpl::OnShellDestroying() {
 }
 
 void AppListControllerImpl::OnOverviewModeStarting() {
-  if (!IsHomeScreenAvailable())
+  if (!IsTabletMode())
     DismissAppList();
 }
 
@@ -665,7 +661,6 @@ void AppListControllerImpl::OnDisplayConfigurationChanged() {
   // expected if it's enabled and we're still in tablet mode.
   // https://crbug.com/900956.
   const bool should_be_shown = IsTabletMode();
-  DCHECK_EQ(should_be_shown, IsHomeScreenAvailable());
   if (should_be_shown == GetTargetVisibility())
     return;
 
@@ -706,7 +701,7 @@ void AppListControllerImpl::OnUiVisibilityChanged(
       // When Launcher is closing, we do not want to call
       // |ShowEmbeddedAssistantUI(false)|, which will show previous state page
       // in Launcher and make the UI flash.
-      if (IsHomeScreenAvailable()) {
+      if (IsTabletMode()) {
         base::Optional<
             app_list::ContentsView::ScopedSetActiveStateAnimationDisabler>
             set_active_state_animation_disabler;
@@ -811,7 +806,7 @@ ash::ShelfAction AppListControllerImpl::OnHomeButtonPressed(
     int64_t display_id,
     app_list::AppListShowSource show_source,
     base::TimeTicks event_time_stamp) {
-  if (!IsHomeScreenAvailable())
+  if (!IsTabletMode())
     return ToggleAppList(display_id, show_source, event_time_stamp);
 
   bool handled = Shell::Get()->home_screen_controller()->GoHome(display_id);
@@ -830,9 +825,9 @@ bool AppListControllerImpl::IsShowingEmbeddedAssistantUI() const {
 void AppListControllerImpl::UpdateExpandArrowVisibility() {
   bool should_show = false;
 
-  // Hide the expand arrow view when the home screen is available and there is
-  // no activatable window on the current active desk.
-  if (IsHomeScreenAvailable()) {
+  // Hide the expand arrow view when in tablet mode and there is no activatable
+  // window on the current active desk.
+  if (IsTabletMode()) {
     should_show = !ash::Shell::Get()
                        ->mru_window_tracker()
                        ->BuildWindowForCycleList(kActiveDesk)
@@ -884,7 +879,7 @@ void AppListControllerImpl::StartAssistant() {
     return;
   }
 
-  if (!IsHomeScreenAvailable())
+  if (!IsTabletMode())
     DismissAppList();
 
   ash::Shell::Get()->assistant_controller()->ui_controller()->ShowUi(
@@ -1394,8 +1389,7 @@ void AppListControllerImpl::UpdateAssistantVisibility() {
 }
 
 int64_t AppListControllerImpl::GetDisplayIdToShowAppListOn() {
-  if (IsHomeScreenAvailable() &&
-      !Shell::Get()->display_manager()->IsInUnifiedMode()) {
+  if (IsTabletMode() && !Shell::Get()->display_manager()->IsInUnifiedMode()) {
     return display::Display::HasInternalDisplay()
                ? display::Display::InternalDisplayId()
                : display::Screen::GetScreen()->GetPrimaryDisplay().id();
@@ -1407,7 +1401,7 @@ int64_t AppListControllerImpl::GetDisplayIdToShowAppListOn() {
 }
 
 void AppListControllerImpl::ResetHomeLauncherIfShown() {
-  if (!IsHomeScreenAvailable() || !presenter_.IsVisible())
+  if (!IsTabletMode() || !presenter_.IsVisible())
     return;
 
   auto* const keyboard_controller = keyboard::KeyboardUIController::Get();
@@ -1462,7 +1456,7 @@ aura::Window* AppListControllerImpl::GetContainerForDisplayId(
 }
 
 bool AppListControllerImpl::ShouldLauncherShowBehindApps() const {
-  return IsHomeScreenAvailable() &&
+  return IsTabletMode() &&
          model_->state() != ash::AppListState::kStateEmbeddedAssistant;
 }
 

ash/home_screen/home_screen_controller.cc

@@ -58,12 +58,8 @@ HomeScreenController::~HomeScreenController() {
   Shell::Get()->overview_controller()->RemoveObserver(this);
 }
 
-bool HomeScreenController::IsHomeScreenAvailable() {
-  return Shell::Get()->tablet_mode_controller()->InTabletMode();
-}
-
 void HomeScreenController::Show() {
-  DCHECK(IsHomeScreenAvailable());
+  DCHECK(Shell::Get()->tablet_mode_controller()->InTabletMode());
 
   if (!Shell::Get()->session_controller()->IsActiveUserSessionStarted())
     return;
@@ -77,7 +73,7 @@ void HomeScreenController::Show() {
 }
 
 bool HomeScreenController::GoHome(int64_t display_id) {
-  DCHECK(IsHomeScreenAvailable());
+  DCHECK(Shell::Get()->tablet_mode_controller()->InTabletMode());
 
   if (home_launcher_gesture_handler_->ShowHomeLauncher(
           Shell::Get()->display_manager()->GetDisplayForId(display_id))) {
@@ -160,7 +156,7 @@ void HomeScreenController::OnWallpaperPreviewEnded() {
 }
 
 void HomeScreenController::UpdateVisibility() {
-  if (!IsHomeScreenAvailable())
+  if (!Shell::Get()->tablet_mode_controller()->InTabletMode())
     return;
 
   aura::Window* window = delegate_->GetHomeScreenWindow();

ash/home_screen/home_screen_controller.h

@@ -27,10 +27,6 @@ class ASH_EXPORT HomeScreenController : public OverviewObserver,
   HomeScreenController();
   ~HomeScreenController() override;
 
-  // Returns true if the home screen can be shown (generally corresponds to the
-  // device being in tablet mode).
-  bool IsHomeScreenAvailable();
-
   // Shows the home screen.
   void Show();
 

ash/shelf/home_button_controller.cc

@@ -31,7 +31,7 @@ namespace {
 
 // Returns true if the button should appear activatable.
 bool CanActivate() {
-  return Shell::Get()->home_screen_controller()->IsHomeScreenAvailable() ||
+  return Shell::Get()->tablet_mode_controller()->InTabletMode() ||
          !Shell::Get()->app_list_controller()->IsVisible();
 }
 
@@ -172,9 +172,9 @@ void HomeButtonController::StartAssistantAnimation() {
 }
 
 void HomeButtonController::OnAppListShown() {
-  // Do not show a highlight if the home screen is available, since the home
-  // screen view is always open in the background.
-  if (!Shell::Get()->home_screen_controller()->IsHomeScreenAvailable())
+  // Do not show a highlight in tablet mode, since the home screen view is
+  // always open in the background.
+  if (!Shell::Get()->tablet_mode_controller()->InTabletMode())
     button_->AnimateInkDrop(views::InkDropState::ACTIVATED, nullptr);
   is_showing_app_list_ = true;
   RootWindowController::ForWindow(button_->GetWidget()->GetNativeWindow())

ash/shelf/shelf_layout_manager.cc

@@ -106,25 +106,14 @@ bool IsAppListWindow(const aura::Window* window) {
 bool IsTabletModeEnabled() {
   // Shell could be destroying. Shell destroys TabletModeController before
   // closing all windows.
-  if (!Shell::Get()->tablet_mode_controller())
-    return false;
-
-  return Shell::Get()->tablet_mode_controller()->InTabletMode();
+  return Shell::Get()->tablet_mode_controller() &&
+         Shell::Get()->tablet_mode_controller()->InTabletMode();
 }
 
 bool IsHotseatEnabled() {
   return IsTabletModeEnabled() && chromeos::switches::ShouldShowShelfHotseat();
 }
 
-bool IsHomeScreenAvailable() {
-  // Shell could be destroying. Shell destroys HomeScreenController before
-  // closing all windows.
-  if (!Shell::Get() || !Shell::Get()->home_screen_controller())
-    return false;
-
-  return Shell::Get()->home_screen_controller()->IsHomeScreenAvailable();
-}
-
 // Returns the |WorkspaceWindowState| of the currently active desk on the root
 // window of |shelf_window|.
 WorkspaceWindowState GetShelfWorkspaceWindowState(aura::Window* shelf_window) {
@@ -632,7 +621,7 @@ ShelfBackgroundType ShelfLayoutManager::GetShelfBackgroundType() const {
             ->home_screen_controller()
             ->home_launcher_gesture_handler()
             ->GetActiveWindow());
-  if (IsHomeScreenAvailable()) {
+  if (IsTabletModeEnabled()) {
     // If the home launcher is shown, being animated, or dragged, show the
     // default background.
     if (is_app_list_visible_ || home_launcher_animation_state_ == kShowing)
@@ -1638,7 +1627,7 @@ ShelfAutoHideState ShelfLayoutManager::CalculateAutoHideState(
   if (shelf_->auto_hide_lock())
     return state_.auto_hide_state;
 
-  if (shelf_widget_->IsShowingAppList() && !IsHomeScreenAvailable())
+  if (shelf_widget_->IsShowingAppList() && !IsTabletModeEnabled())
     return SHELF_AUTO_HIDE_SHOWN;
 
   if (shelf_widget_->status_area_widget() &&
@@ -1781,7 +1770,7 @@ float ShelfLayoutManager::ComputeTargetOpacity(const State& state) const {
 bool ShelfLayoutManager::IsShelfHiddenForFullscreen() const {
   // If the non-fullscreen app list should be shown, the shelf should not be
   // hidden.
-  if (!IsHomeScreenAvailable() &&
+  if (!IsTabletModeEnabled() &&
       Shell::Get()->app_list_controller()->GetTargetVisibility()) {
     return false;
   }
@@ -1957,7 +1946,7 @@ bool ShelfLayoutManager::StartAppListDrag(
     float scroll_y_hint) {
   // If the home screen is available, gesture dragging is handled by
   // HomeLauncherGestureHandler.
-  if (IsHomeScreenAvailable() && event_in_screen.IsGestureEvent())
+  if (IsTabletModeEnabled() && event_in_screen.IsGestureEvent())
     return false;
 
   // Fullscreen app list can only be dragged from bottom alignment shelf.
@@ -2002,7 +1991,7 @@ bool ShelfLayoutManager::StartAppListDrag(
 bool ShelfLayoutManager::StartShelfDrag(
     const ui::LocatedEvent& event_in_screen) {
   // Disable the shelf dragging if the fullscreen app list is opened.
-  if (is_app_list_visible_ && !IsHomeScreenAvailable())
+  if (is_app_list_visible_ && !IsTabletModeEnabled())
     return false;
 
   // Also disable shelf drags until the overflow shelf is closed.