Bento: AltTabMode: Hide interactive alt-tab mode for one desk

- When user has only one desk, mode switching should be off and
the tab slider should be hidden.
- Add Ash unit tests to check visibility and existence of the
interactive component when the number of desks changes.

Bug: 1161243
Test: Manual test (see a video in crbug) and Ash unit tests
`ash_unittests --gtest_filter=ModeSelectionWindowCycleControllerTest.SingleDeskHidesInteractiveMode`

Change-Id: I32708306cd310d4075ee9bbb20991e3bad20531f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2603854
Commit-Queue: Cattalyya Nuengsigkapian <cattalyya@chromium.org>
Reviewed-by: Xiaoqian Dai <xdai@chromium.org>
Reviewed-by: Min Chen <minch@chromium.org>
Cr-Commit-Position: refs/heads/master@{#840903}

ash/wm/window_cycle/window_cycle_controller.cc

@@ -173,8 +173,7 @@ WindowCycleController::WindowList WindowCycleController::CreateWindowList() {
 }
 
 void WindowCycleController::SetAltTabMode(DesksMruType alt_tab_mode) {
-  DCHECK(features::IsBentoEnabled());
-  if (alt_tab_mode_ == alt_tab_mode)
+  if (!IsInteractiveAltTabModeAllowed() || alt_tab_mode_ == alt_tab_mode)
     return;
   alt_tab_mode_ = alt_tab_mode;
   MaybeResetCycleList();
@@ -192,9 +191,15 @@ bool WindowCycleController::IsSwitchingMode() {
   return features::IsBentoEnabled() && is_switching_mode_;
 }
 
+bool WindowCycleController::IsInteractiveAltTabModeAllowed() {
+  return features::IsBentoEnabled() &&
+         Shell::Get()->desks_controller()->GetNumberOfDesks() > 1;
+}
+
 bool WindowCycleController::IsAltTabPerActiveDesk() {
-  return features::IsBentoEnabled() ? alt_tab_mode_ == kActiveDesk
-                                    : features::IsAltTabLimitedToActiveDesk();
+  return IsInteractiveAltTabModeAllowed()
+             ? alt_tab_mode_ == kActiveDesk
+             : features::IsAltTabLimitedToActiveDesk();
 }
 
 void WindowCycleController::SaveCurrentActiveDeskAndWindow(

ash/wm/window_cycle/window_cycle_controller.h

@@ -90,9 +90,14 @@ class ASH_EXPORT WindowCycleController {
   // Sets alt-tab mode to all desks (default) or active desk.
   void SetAltTabMode(DesksMruType alt_tab_mode_);
 
-  // Checks if alt-tab should be per active desk. If Bento is enabled, alt-tab
-  // mode depends on users' alt_tab_mode_ selection. Otherwise, it'll default
-  // to all desk unless LimitAltTabToActiveDesk flag is explicitly enabled.
+  // Checks if switching between alt-tab mode via the tab slider is allowed.
+  // Returns true if Bento flag is enabled and users have multiple desks.
+  bool IsInteractiveAltTabModeAllowed();
+
+  // Checks if alt-tab should be per active desk. If
+  // `IsInteractiveAltTabModeAllowed()`, alt-tab mode depends on users'
+  // |alt_tab_mode_| selection. Otherwise, it'll default to all desk unless
+  // LimitAltTabToActiveDesk flag is explicitly enabled.
   bool IsAltTabPerActiveDesk();
 
   // Returns true while switching the alt-tab mode and Bento flag is enabled.

ash/wm/window_cycle/window_cycle_controller_unittest.cc

@@ -1386,6 +1386,63 @@ class ModeSelectionWindowCycleControllerTest
   ui::test::EventGenerator* generator_;
 };
 
+// Tests that if user uses only one desk, the tab slider and no recent items
+// are not shown. Moreover, `SetAltTabMode()` should not change the windows
+// list.
+TEST_F(ModeSelectionWindowCycleControllerTest, SingleDeskHidesInteractiveMode) {
+  WindowCycleController* cycle_controller =
+      Shell::Get()->window_cycle_controller();
+
+  // Create two windows in the current desk.
+  auto win0 = CreateAppWindow(gfx::Rect(0, 0, 250, 100));
+  auto win1 = CreateAppWindow(gfx::Rect(50, 50, 200, 200));
+  auto* desks_controller = DesksController::Get();
+  ASSERT_EQ(1u, desks_controller->desks().size());
+
+  // Alt-tab should contain windows from all desks without any the tab slider
+  // and no-recent-items view.
+  cycle_controller->StartCycling();
+  EXPECT_TRUE(!GetWindowCycleNoRecentItemsLabel());
+  EXPECT_FALSE(cycle_controller->IsAltTabPerActiveDesk());
+  auto cycle_windows = GetWindows(cycle_controller);
+  EXPECT_EQ(2u, cycle_windows.size());
+  EXPECT_EQ(cycle_windows.size(), GetWindowCycleItemViews().size());
+  const gfx::Rect alttab_bounds_without_tab_slider =
+      GetWindowCycleListWidget()->GetWindowBoundsInScreen();
+  cycle_controller->CompleteCycling();
+
+  // Create an empty desk_2 and start alt-tab to enter the all-desks mode.
+  desks_controller->NewDesk(DesksCreationRemovalSource::kButton);
+  const Desk* desk_2 = desks_controller->desks()[1].get();
+  ActivateDesk(desk_2);
+  EXPECT_EQ(desk_2, desks_controller->active_desk());
+  cycle_controller->StartCycling();
+  EXPECT_FALSE(cycle_controller->IsAltTabPerActiveDesk());
+  EXPECT_EQ(2u, cycle_windows.size());
+  EXPECT_EQ(cycle_windows.size(), GetWindowCycleItemViews().size());
+
+  // Expect mode-switching buttons and no-recent-item label to exist.
+  EXPECT_FALSE(!GetWindowCycleNoRecentItemsLabel());
+  auto tab_slider_buttons = GetWindowCycleTabSliderViews();
+  EXPECT_EQ(2u, tab_slider_buttons.size());
+  const gfx::Rect alttab_bounds_with_tab_slider =
+      GetWindowCycleListWidget()->GetWindowBoundsInScreen();
+  const int window_cycle_list_y =
+      GetWindowCycleItemViews()[0]->GetBoundsInScreen().y();
+  const gfx::Rect tab_slider_button_bound =
+      tab_slider_buttons[0]->GetBoundsInScreen();
+  // Expect that alt-tab views height is larger due to the tab slider insertion
+  // and expect that window cycle list is placed below the tab slider.
+  EXPECT_LT(alttab_bounds_without_tab_slider.height(),
+            alttab_bounds_with_tab_slider.height());
+  EXPECT_LT(tab_slider_button_bound.y() + tab_slider_button_bound.height(),
+            window_cycle_list_y);
+
+  DeskSwitchAnimationWaiter waiter;
+  cycle_controller->CompleteCycling();
+  waiter.Wait();
+}
+
 // Tests that alt-tab shows all windows in an all-desk mode by default and
 // shows only windows in the current desk in a current-desk mode. Switching
 // between two modes should refresh the window list, while re-entering alt-tab

ash/wm/window_cycle/window_cycle_list.cc

@@ -279,7 +279,9 @@ class WindowCycleView : public views::WidgetDelegateView,
     layer->SetBackdropFilterQuality(kBackgroundBlurQuality);
     layer->SetName("WindowCycleView");
 
-    if (features::IsBentoEnabled()) {
+    if (Shell::Get()
+            ->window_cycle_controller()
+            ->IsInteractiveAltTabModeAllowed()) {
       tab_slider_container_ =
           AddChildView(std::make_unique<WindowCycleTabSlider>());
 
@@ -312,7 +314,9 @@ class WindowCycleView : public views::WidgetDelegateView,
     views::BoxLayout* layout =
         mirror_container_->SetLayoutManager(std::make_unique<views::BoxLayout>(
             views::BoxLayout::Orientation::kHorizontal,
-            gfx::Insets(features::IsBentoEnabled()
+            gfx::Insets(Shell::Get()
+                                ->window_cycle_controller()
+                                ->IsInteractiveAltTabModeAllowed()
                             ? kMirrorContainerVerticalPaddingDp
                             : kInsideBorderVerticalPaddingDp,
                         kInsideBorderHorizontalPaddingDp,
@@ -347,14 +351,13 @@ class WindowCycleView : public views::WidgetDelegateView,
 
   void UpdateWindows(const WindowCycleList::WindowList& windows) {
     const bool no_windows = windows.empty();
-    if (features::IsBentoEnabled()) {
+    if (Shell::Get()
+            ->window_cycle_controller()
+            ->IsInteractiveAltTabModeAllowed()) {
       no_recent_items_label_->SetVisible(no_windows);
     }
     if (no_windows)
       return;
-
-    if (features::IsBentoEnabled())
-      no_recent_items_label_->SetVisible(false);
     for (auto* window : windows) {
       auto* view = mirror_container_->AddChildView(
           std::make_unique<WindowCycleItemView>(window));
@@ -449,7 +452,9 @@ class WindowCycleView : public views::WidgetDelegateView,
   // views::WidgetDelegateView:
   gfx::Size CalculatePreferredSize() const override {
     gfx::Size size = mirror_container_->GetPreferredSize();
-    if (features::IsBentoEnabled()) {
+    if (Shell::Get()
+            ->window_cycle_controller()
+            ->IsInteractiveAltTabModeAllowed()) {
       size.Enlarge(0, tab_slider_container_->GetPreferredSize().height() +
                           kTabSliderContainerVerticalPaddingDp);
     }
@@ -496,7 +501,9 @@ class WindowCycleView : public views::WidgetDelegateView,
     container_bounds.set_x(x_offset);
 
     // Layout a tab slider if Bento is enabled.
-    if (features::IsBentoEnabled()) {
+    if (Shell::Get()
+            ->window_cycle_controller()
+            ->IsInteractiveAltTabModeAllowed()) {
       // Layout the tab slider.
       const gfx::Size tab_slider_size =
           tab_slider_container_->GetPreferredSize();