Revert "Bento: AltTabMode: Update highlighted window after switching mode."

This reverts commit c83fe85c.

Reason for revert: Made 	ModeSelectionWindowCycleControllerTest.CycleShowsWindowsPerMode flaky.
https://ci.chromium.org/p/chromium/builders/ci/linux-chromeos-dbg/22082

Original change's description:
> Bento: AltTabMode: Update highlighted window after switching mode.
>
> Regardless of where the highlight position is, after switching
> alt-tab mode, the highlight will be reset to the first or second
> window. This is consistent with highlighting when users first
> enter alt-tab mode:
> - In general case, highlight the second (next) most recently used
> window after the current one.
> - In the special case that the most recently used is minimized,
> highlight itself (the MRU window), so tabbing into it causes it
> to unminimize rather than opening up the next window in the list.
>
> - Track mode switching state in the controller to differentiate
> between normal tab pressing and mode switching.
> - Add Ash unit tests for both cases.
>
> `ash_unittests --gtest_filter=ModeSelectionWindowCycleControllerTest.SwitchingModeUpdates*WindowHighlight`
>
> Bug: 1157100
> Test: Manual test (a video uploaded to crbug) and ash unit tests
> Change-Id: Id85b389ba9d59eb1815b8250d640e5aa9128240b
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2604907
> Reviewed-by: Xiaoqian Dai <xdai@chromium.org>
> Reviewed-by: Min Chen <minch@chromium.org>
> Commit-Queue: Cattalyya Nuengsigkapian <cattalyya@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#840348}

TBR=xdai@chromium.org,minch@chromium.org,chromium-scoped@luci-project-accounts.iam.gserviceaccount.com,cattalyya@chromium.org

Change-Id: I2551bf6393988d2ee1f790f2f39fdeae9cb0abba
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1157100
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2611090Reviewed-by: Morten Stenshorne <mstensho@chromium.org>
Commit-Queue: Morten Stenshorne <mstensho@chromium.org>
Cr-Commit-Position: refs/heads/master@{#840560}

ash/wm/window_cycle/window_cycle_controller.cc

@@ -89,6 +89,8 @@ void WindowCycleController::HandleCycleWindow(Direction direction) {
   if (!IsCycling())
     StartCycling();
 
+  // TODO(crbug.com/1157100): Handle window highlighting after switching
+  // alt-tab mode.
   Step(direction);
 }
 
@@ -173,23 +175,10 @@ WindowCycleController::WindowList WindowCycleController::CreateWindowList() {
 }
 
 void WindowCycleController::SetAltTabMode(DesksMruType alt_tab_mode) {
-  DCHECK(features::IsBentoEnabled());
   if (alt_tab_mode_ == alt_tab_mode)
     return;
   alt_tab_mode_ = alt_tab_mode;
   MaybeResetCycleList();
-
-  is_switching_mode_ = true;
-  // When user first press alt + tab, `HandleCycleForwardMRU` triggers
-  // `HandleCycleWindow(WindowCycleController::FORWARD)` since it considers
-  // the initial tab as forward cycling. Therefore, switching the mode
-  // should imitate the same forward cycling behavior after the cycle is reset.
-  HandleCycleWindow(WindowCycleController::FORWARD);
-  is_switching_mode_ = false;
-}
-
-bool WindowCycleController::IsSwitchingMode() {
-  return features::IsBentoEnabled() && is_switching_mode_;
 }
 
 bool WindowCycleController::IsAltTabPerActiveDesk() {

ash/wm/window_cycle/window_cycle_controller.h

@@ -95,12 +95,6 @@ class ASH_EXPORT WindowCycleController {
   // to all desk unless LimitAltTabToActiveDesk flag is explicitly enabled.
   bool IsAltTabPerActiveDesk();
 
-  // Returns true while switching the alt-tab mode and Bento flag is enabled.
-  // This helps `Scroll()` and `Step()` distinguish between pressing tabs and
-  // switching mode, so they refresh |current_index_| and the highlighted
-  // window correctly.
-  bool IsSwitchingMode();
-
  private:
   // Gets a list of windows from the currently open windows, removing windows
   // with transient roots already in the list. The returned list of windows
@@ -136,9 +130,6 @@ class ASH_EXPORT WindowCycleController {
   // TODO(crbug.com/1157105): Store per-desk mode in primary user pref.
   DesksMruType alt_tab_mode_ = DesksMruType::kAllDesks;
 
-  // Tracks whether alt-tab mode is currently switching or not.
-  bool is_switching_mode_ = false;
-
   DISALLOW_COPY_AND_ASSIGN(WindowCycleController);
 };
 

ash/wm/window_cycle/window_cycle_controller_unittest.cc

@@ -1540,132 +1540,4 @@ TEST_F(ModeSelectionWindowCycleControllerTest, NoWindowInActiveDesk) {
   waiter.Wait();
 }
 
-// Tests that switching between modes correctly reset the alt-tab-highlighted
-// window to the second most recently used window, i.e. the next window to tab
-// into from the currently used window. Since the window cycle list is ordered
-// by MRU, such window is therefore the second window in the MRU list.
-TEST_F(ModeSelectionWindowCycleControllerTest,
-       SwitchingModeUpdatesWindowHighlight) {
-  WindowCycleController* cycle_controller =
-      Shell::Get()->window_cycle_controller();
-
-  // Create two windows for desk1 and three windows for desk2 in the reversed
-  // order of the most recently active window.
-  auto win4 = CreateAppWindow(gfx::Rect(0, 0, 250, 100));
-  auto win3 = CreateAppWindow(gfx::Rect(50, 50, 200, 200));
-  auto* desks_controller = DesksController::Get();
-  desks_controller->NewDesk(DesksCreationRemovalSource::kButton);
-  ASSERT_EQ(2u, desks_controller->desks().size());
-  const Desk* desk_2 = desks_controller->desks()[1].get();
-  ActivateDesk(desk_2);
-  EXPECT_EQ(desk_2, desks_controller->active_desk());
-  auto win2 = CreateAppWindow(gfx::Rect(0, 0, 300, 200));
-  auto win1 = CreateAppWindow(gfx::Rect(10, 30, 400, 200));
-  auto win0 = CreateAppWindow(gfx::Rect(10, 30, 400, 200));
-
-  // Enter the all-desk mode by default with the window order [0, 1, 2, 3 ,4].
-  cycle_controller->StartCycling();
-  cycle_controller->HandleCycleWindow(WindowCycleController::FORWARD);
-
-  EXPECT_FALSE(cycle_controller->IsAltTabPerActiveDesk());
-  auto cycle_windows = GetWindows(cycle_controller);
-  // The window list is MRU ordered.
-  EXPECT_EQ(win0.get(), cycle_windows[0]);
-  EXPECT_EQ(win1.get(), cycle_windows[1]);
-  EXPECT_EQ(win2.get(), cycle_windows[2]);
-  EXPECT_EQ(win3.get(), cycle_windows[3]);
-  EXPECT_EQ(win4.get(), cycle_windows[4]);
-  // Alt-Tab should highlight the second most recently used window, which is
-  // the second window in the MRU list, win1.
-  EXPECT_EQ(win1.get(), GetTargetWindow());
-
-  // Step to win2 and win3, so we are now select a window in a non-active desk.
-  cycle_controller->HandleCycleWindow(WindowCycleController::FORWARD);
-  EXPECT_EQ(win2.get(), GetTargetWindow());
-  cycle_controller->HandleCycleWindow(WindowCycleController::FORWARD);
-  EXPECT_EQ(win3.get(), GetTargetWindow());
-
-  // Switching from the all-desks mode, which highlights a non-current-desk
-  // window to the current-desk mode [0, 1, 2] should resolve the highlight
-  // correctly to win1, the second window in the cycle list.
-  SwitchPerDeskAltTabMode(true);
-  EXPECT_EQ(win1.get(), GetTargetWindow());
-  EXPECT_EQ(win1.get(), cycle_windows[1]);
-  // Step to win2.
-  cycle_controller->HandleCycleWindow(WindowCycleController::FORWARD);
-  EXPECT_EQ(win2.get(), GetTargetWindow());
-
-  // Switching back to the all-desk mode should reset highlight to win1 again.
-  SwitchPerDeskAltTabMode(false);
-  EXPECT_EQ(win1.get(), GetTargetWindow());
-  cycle_controller->CompleteCycling();
-}
-
-// Similar to `SwitchingModeUpdatesWindowHighlight`, tests that switching the
-// alt-tab mode updates the highlighted window to the first window (most
-// recently used) in the special case where all windows are minimized.
-// When they are minimized, cycling forward should help unminimize the most
-// recently used window rather than trying to open the second most recently
-// used window.
-TEST_F(ModeSelectionWindowCycleControllerTest,
-       SwitchingModeUpdatesMinimizedWindowHighlight) {
-  WindowCycleController* cycle_controller =
-      Shell::Get()->window_cycle_controller();
-
-  // Create two windows for desk1 and three windows for desk2 in the reversed
-  // order of the most recently active window.
-  auto win4 = CreateAppWindow(gfx::Rect(0, 0, 250, 100));
-  auto win3 = CreateAppWindow(gfx::Rect(50, 50, 200, 200));
-  auto* desks_controller = DesksController::Get();
-  desks_controller->NewDesk(DesksCreationRemovalSource::kButton);
-  ASSERT_EQ(2u, desks_controller->desks().size());
-  const Desk* desk_2 = desks_controller->desks()[1].get();
-  ActivateDesk(desk_2);
-  EXPECT_EQ(desk_2, desks_controller->active_desk());
-  auto win2 = CreateAppWindow(gfx::Rect(0, 0, 300, 200));
-  auto win1 = CreateAppWindow(gfx::Rect(10, 30, 400, 200));
-  auto win0 = CreateAppWindow(gfx::Rect(10, 30, 400, 200));
-
-  // Minimize all windows to test this special case.
-  WindowState::Get(win4.get())->Minimize();
-  WindowState::Get(win3.get())->Minimize();
-  WindowState::Get(win2.get())->Minimize();
-  WindowState::Get(win1.get())->Minimize();
-  WindowState::Get(win0.get())->Minimize();
-  EXPECT_FALSE(WindowState::Get(win0.get())->IsActive());
-  EXPECT_FALSE(WindowState::Get(win1.get())->IsActive());
-  EXPECT_FALSE(WindowState::Get(win2.get())->IsActive());
-  EXPECT_FALSE(WindowState::Get(win3.get())->IsActive());
-  EXPECT_FALSE(WindowState::Get(win4.get())->IsActive());
-
-  // Enter the all-desk mode by default with the window order [0, 1, 2, 3 ,4].
-  cycle_controller->HandleCycleWindow(WindowCycleController::FORWARD);
-  EXPECT_FALSE(cycle_controller->IsAltTabPerActiveDesk());
-  auto cycle_windows = GetWindows(cycle_controller);
-  EXPECT_EQ(5u, GetWindowCycleItemViews().size());
-  // The window list is MRU ordered.
-  EXPECT_EQ(win0.get(), cycle_windows[0]);
-  EXPECT_EQ(win1.get(), cycle_windows[1]);
-  EXPECT_EQ(win2.get(), cycle_windows[2]);
-  EXPECT_EQ(win3.get(), cycle_windows[3]);
-  EXPECT_EQ(win4.get(), cycle_windows[4]);
-  // Step forward a few times and switch to all-desks mode. This should
-  // highlight win0, the first window in the current-desk cycle list.
-  cycle_controller->HandleCycleWindow(WindowCycleController::FORWARD);
-  cycle_controller->HandleCycleWindow(WindowCycleController::FORWARD);
-  SwitchPerDeskAltTabMode(true);
-  EXPECT_EQ(3u, GetWindowCycleItemViews().size());
-  EXPECT_EQ(win0.get(), GetTargetWindow());
-  EXPECT_EQ(win0.get(), cycle_windows[0]);
-
-  // Stepping to win1 and switching back to the all-desk mode should reset
-  // a highlight to win0 again.
-  cycle_controller->HandleCycleWindow(WindowCycleController::FORWARD);
-  EXPECT_EQ(win1.get(), GetTargetWindow());
-  SwitchPerDeskAltTabMode(false);
-  EXPECT_EQ(5u, GetWindowCycleItemViews().size());
-  EXPECT_EQ(win0.get(), GetTargetWindow());
-  cycle_controller->CompleteCycling();
-}
-
 }  // namespace ash

ash/wm/window_cycle/window_cycle_list.cc

@@ -690,16 +690,7 @@ void WindowCycleList::Step(WindowCycleController::Direction direction) {
   }
 
   const int offset = direction == WindowCycleController::FORWARD ? 1 : -1;
-  if (offset == 1 && !wm::IsActiveWindow(windows_[0]) &&
-      Shell::Get()->window_cycle_controller()->IsSwitchingMode()) {
-    // Similar to `WindowCycleList::Scroll()`, when switching to alt-tab mode,
-    // if all windows are minimized, the starting window should be the first
-    // one rather than the second. Note that during entering alt-tab mode,
-    // `SetFocusedWindow()` does nothing, so we don't need to prevent it here.
-    SetFocusedWindow(windows_[0]);
-  } else {
-    SetFocusedWindow(windows_[GetOffsettedWindowIndex(offset)]);
-  }
+  SetFocusedWindow(windows_[GetOffsettedWindowIndex(offset)]);
   Scroll(offset);
 }
 
@@ -884,17 +875,16 @@ void WindowCycleList::Scroll(int offset) {
 
   DCHECK(static_cast<size_t>(current_index_) < windows_.size());
 
-  // If alt-tab is entered or switched to the other mode, check the following
-  // special case: user is cycling forward but the MRU window is not active.
-  // This occurs when all windows are minimized. The starting window should be
-  // the first one rather than the second.
-  if ((!cycle_view_ ||
-       Shell::Get()->window_cycle_controller()->IsSwitchingMode()) &&
-      current_index_ == 0 && offset == 1 && !wm::IsActiveWindow(windows_[0])) {
-    current_index_ = -1;
+  if (!cycle_view_ && current_index_ == 0) {
+    // Special case the situation where we're cycling forward but the MRU
+    // window is not active. This occurs when all windows are minimized. The
+    // starting window should be the first one rather than the second.
+    if (offset == 1 && !wm::IsActiveWindow(windows_[0]))
+      current_index_ = -1;
   }
 
   current_index_ = GetOffsettedWindowIndex(offset);
+
   if (ShouldShowUi()) {
     if (current_index_ > 1)
       InitWindowCycleView();