split view: Adjust logic of when overview shall not steal focus at start

The present CL follows up after [1] about overview not stealing focus
from a window snapped in split view. The present CL makes the solution
simpler and less error prone.

[1] https://chromium-review.googlesource.com/c/chromium/src/+/1756550

Test: ash_unittests TabletModeControllerTest.StartSplitViewAndThenOverview
Bug: 993403
Change-Id: I9c25fbdfa8fd63050769817e1e2b4380389bd015
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1768833Reviewed-by: Ahmed Fakhry <afakhry@chromium.org>
Commit-Queue: Avery Musbach <amusbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#691881}

ash/wm/overview/overview_controller.cc

@@ -643,6 +643,21 @@ bool OverviewController::ToggleOverview(
       OnEndingAnimationComplete(/*canceled=*/true);
     delayed_animations_.clear();
 
+    // |should_focus_overview_| shall be true except when split view mode starts
+    // on transition between clamshell mode and tablet mode, on transition
+    // between user sessions, or on transition between virtual desks. Those are
+    // the cases where code arranges split view by first snapping a window on
+    // one side and then starting overview to be seen on the other side, meaning
+    // that the split view state here will be |SplitViewState::kLeftSnapped| or
+    // |SplitViewState::kRightSnapped|. We have to check the split view state
+    // before |SplitViewController::OnOverviewModeStarting|, because in case of
+    // |SplitViewState::kBothSnapped|, that function will insert one of the two
+    // snapped windows to overview.
+    const SplitViewState split_view_state =
+        Shell::Get()->split_view_controller()->state();
+    should_focus_overview_ = split_view_state == SplitViewState::kNoSnap ||
+                             split_view_state == SplitViewState::kBothSnapped;
+
     // Suspend occlusion tracker until the enter animation is complete.
     PauseOcclusionTracker();
 
@@ -706,8 +721,10 @@ void OverviewController::OnStartingAnimationComplete(bool canceled) {
 
   for (auto& observer : observers_)
     observer.OnOverviewModeStartingAnimationComplete(canceled);
-  if (overview_session_)
-    overview_session_->OnStartingAnimationComplete(canceled);
+  if (overview_session_) {
+    overview_session_->OnStartingAnimationComplete(canceled,
+                                                   should_focus_overview_);
+  }
   UnpauseOcclusionTracker(kOcclusionPauseDurationForStartMs);
   TRACE_EVENT_ASYNC_END1("ui", "OverviewController::EnterOverview", this,
                          "canceled", canceled);

ash/wm/overview/overview_controller.h

@@ -143,6 +143,10 @@ class ASH_EXPORT OverviewController : public OverviewDelegate,
   // notify shell that the starting animations have been completed.
   std::vector<std::unique_ptr<DelayedAnimationObserver>> start_animations_;
 
+  // Indicates that overview shall gain focus when the starting animations have
+  // completed.
+  bool should_focus_overview_ = false;
+
   std::unique_ptr<aura::WindowOcclusionTracker::ScopedPause>
       occlusion_tracker_pauser_;
 

ash/wm/overview/overview_session.cc

@@ -642,19 +642,20 @@ void OverviewSession::UpdateRoundedCornersAndShadow() {
       window->UpdateRoundedCornersAndShadow();
 }
 
-void OverviewSession::OnStartingAnimationComplete(bool canceled) {
+void OverviewSession::OnStartingAnimationComplete(bool canceled,
+                                                  bool should_focus_overview) {
   for (auto& grid : grid_list_)
     grid->OnStartingAnimationComplete(canceled);
 
-  if (!canceled) {
-    if (overview_focus_widget_) {
-      if (enter_exit_overview_type_ == EnterExitOverviewType::kStartUnfocused)
-        overview_focus_widget_->ShowInactive();
-      else
-        overview_focus_widget_->Show();
-    }
-    Shell::Get()->overview_controller()->DelayedUpdateRoundedCornersAndShadow();
+  if (canceled)
+    return;
+  if (overview_focus_widget_) {
+    if (should_focus_overview)
+      overview_focus_widget_->Show();
+    else
+      overview_focus_widget_->ShowInactive();
   }
+  Shell::Get()->overview_controller()->DelayedUpdateRoundedCornersAndShadow();
 }
 
 void OverviewSession::OnWindowActivating(

ash/wm/overview/overview_session.h

@@ -90,10 +90,6 @@ class ASH_EXPORT OverviewSession : public display::DisplayObserver,
     // the source desk is in overview mode, while the target desk is not.
     // This should not be used for entering overview mode.
     kImmediateExit,
-    // Prevents overview from stealing the input focus. Used by code that starts
-    // overview after a window has already been snapped in split view. The
-    // purpose is so that overview does not steal focus from the snapped window.
-    kStartUnfocused,
   };
 
   // Callback which fills out the passed settings object. Used by several
@@ -215,8 +211,12 @@ class ASH_EXPORT OverviewSession : public display::DisplayObserver,
   // Updates all the overview items' mask and shadow.
   void UpdateRoundedCornersAndShadow();
 
-  // Called when the overview mode starting animation completes.
-  void OnStartingAnimationComplete(bool canceled);
+  // Called when the overview mode starting animation completes. |canceled| is
+  // true when the starting animation is interrupted by ending overview mode. If
+  // |canceled| is false and |should_focus_overview| is true, then
+  // |overview_focus_widget_| shall gain focus. |should_focus_overview| has no
+  // effect when |canceled| is true.
+  void OnStartingAnimationComplete(bool canceled, bool should_focus_overview);
 
   // Called when windows are being activated/deactivated during
   // overview mode.

ash/wm/tablet_mode/tablet_mode_controller.cc

@@ -17,7 +17,6 @@
 #include "ash/shell.h"
 #include "ash/shell_delegate.h"
 #include "ash/wm/overview/overview_controller.h"
-#include "ash/wm/overview/overview_session.h"
 #include "ash/wm/tablet_mode/internal_input_devices_event_blocker.h"
 #include "ash/wm/tablet_mode/tablet_mode_window_manager.h"
 #include "ash/wm/window_state.h"
@@ -1012,8 +1011,7 @@ void TabletModeController::FinishInitTabletMode() {
   const auto state = Shell::Get()->split_view_controller()->state();
   if (state == SplitViewState::kLeftSnapped ||
       state == SplitViewState::kRightSnapped) {
-    Shell::Get()->overview_controller()->StartOverview(
-        OverviewSession::EnterExitOverviewType::kStartUnfocused);
+    Shell::Get()->overview_controller()->StartOverview();
   }
 
   UpdateInternalInputDevicesEventBlocker();

ash/wm/tablet_mode/tablet_mode_controller_unittest.cc

@@ -1467,18 +1467,6 @@ TEST_F(TabletModeControllerTest, StartTabletActiveLeftSnapPreviousLeftSnap) {
   EXPECT_EQ(window1.get(), window_util::GetActiveWindow());
 }
 
-// Test that it is okay to write code that first starts split view by snapping a
-// window on one side, and then starts overview to be seen on the other side.
-TEST_F(TabletModeControllerTest,
-       ProgrammaticallyStartSplitViewAndThenOverview) {
-  SplitViewController* split_view_controller =
-      Shell::Get()->split_view_controller();
-  tablet_mode_controller()->SetEnabledForTest(true);
-  std::unique_ptr<aura::Window> window = CreateTestWindow();
-  split_view_controller->SnapWindow(window.get(), SplitViewController::LEFT);
-  EXPECT_TRUE(Shell::Get()->overview_controller()->StartOverview());
-}
-
 // Test that tablet mode controller does not respond to the input device changes
 // during its suspend.
 TEST_F(TabletModeControllerTest, DoNotObserverInputDeviceChangeDuringSuspend) {