Don't dismiss app list when showing alt-tab cycler in tablet mode

In tablet mode, the app list is expected to remain visible when
the cycler is shown, so it shouldn't be dismissed.

BUG: 1024494
TEST: Home screen isn't blank after using alt-tab in tablet mode
Change-Id: Iade57ac11528d11501e8b319f2d5dbdbc6716b6e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1927791Reviewed-by: Xiaoqian Dai <xdai@chromium.org>
Reviewed-by: Stefan Kuhne <skuhne@chromium.org>
Commit-Queue: Kazuki Takise <takise@chromium.org>
Auto-Submit: Kazuki Takise <takise@chromium.org>
Cr-Commit-Position: refs/heads/master@{#721751}

ash/wm/window_cycle_controller_unittest.cc

@@ -9,6 +9,7 @@
 
 #include "ash/app_list/test/app_list_test_helper.h"
 #include "ash/focus_cycler.h"
+#include "ash/home_screen/home_screen_controller.h"
 #include "ash/public/cpp/ash_features.h"
 #include "ash/public/cpp/shell_window_ids.h"
 #include "ash/public/cpp/window_properties.h"
@@ -24,6 +25,7 @@
 #include "ash/wm/desks/desk.h"
 #include "ash/wm/desks/desks_controller.h"
 #include "ash/wm/desks/desks_test_util.h"
+#include "ash/wm/tablet_mode/tablet_mode_controller_test_api.h"
 #include "ash/wm/window_cycle_list.h"
 #include "ash/wm/window_state.h"
 #include "ash/wm/window_util.h"
@@ -505,6 +507,25 @@ TEST_F(WindowCycleControllerTest, SelectingHidesAppList) {
   controller->CompleteCycling();
 }
 
+// Tests that beginning window selection doesn't hide the app list in tablet
+// mode.
+TEST_F(WindowCycleControllerTest, SelectingDoesNotHideAppListInTabletMode) {
+  TabletModeControllerTestApi().EnterTabletMode();
+  EXPECT_TRUE(TabletModeControllerTestApi().IsTabletModeStarted());
+  EXPECT_TRUE(Shell::Get()->home_screen_controller()->IsHomeScreenVisible());
+
+  std::unique_ptr<aura::Window> window0(CreateTestWindowInShellWithId(0));
+  std::unique_ptr<aura::Window> window1(CreateTestWindowInShellWithId(1));
+  wm::ActivateWindow(window0.get());
+
+  WindowCycleController* controller = Shell::Get()->window_cycle_controller();
+  controller->HandleCycleWindow(WindowCycleController::FORWARD);
+
+  window0->Hide();
+  window1->Hide();
+  EXPECT_TRUE(Shell::Get()->home_screen_controller()->IsHomeScreenVisible());
+}
+
 // Tests that cycling through windows doesn't change their minimized state.
 TEST_F(WindowCycleControllerTest, CyclePreservesMinimization) {
   WindowCycleController* controller = Shell::Get()->window_cycle_controller();

ash/wm/window_cycle_list.cc

@@ -603,8 +603,9 @@ void WindowCycleList::InitWindowCycleView() {
         widget->GetNativeWindow()->GetRootWindow(),
         std::make_unique<CustomWindowTargeter>(widget->GetNativeWindow()));
   }
-  // Close the app list, if it's open.
-  Shell::Get()->app_list_controller()->DismissAppList();
+  // Close the app list, if it's open in clamshell mode.
+  if (!Shell::Get()->tablet_mode_controller()->InTabletMode())
+    Shell::Get()->app_list_controller()->DismissAppList();
 }
 
 void WindowCycleList::SelectWindow(aura::Window* window) {