overview: Fix focus not correct after closing a split view window.

Test: added test
Bug: 992223
Change-Id: I717921ba2a0cc428b934b57e247f54395691b907
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1750155Reviewed-by: Avery Musbach <amusbach@chromium.org>
Commit-Queue: Sammie Quon <sammiequon@chromium.org>
Cr-Commit-Position: refs/heads/master@{#686463}

ash/wm/overview/overview_session.cc

@@ -881,7 +881,7 @@ void OverviewSession::OnKeyEvent(ui::KeyEvent* event) {
 }
 
 void OverviewSession::OnShellDestroying() {
-  // Cancel selection will call |Shutodnw()|, which will remove observer.
+  // Cancel selection will call |Shutdown()|, which will remove observer.
   EndOverview();
 }
 
@@ -927,6 +927,11 @@ void OverviewSession::OnSplitViewStateChanged(SplitViewState previous_state,
   // Notify |split_view_drag_indicators_| if split view mode ended.
   if (split_view_drag_indicators_ && state == SplitViewState::kNoSnap)
     split_view_drag_indicators_->OnSplitViewModeEnded();
+
+  // Transfer focus from |window| to |overview_focus_widget_| to match the
+  // behavior of entering overview mode in the beginning.
+  DCHECK(overview_focus_widget_);
+  wm::ActivateWindow(GetOverviewFocusWindow());
 }
 
 void OverviewSession::OnSplitViewDividerPositionChanged() {

ash/wm/overview/overview_session_unittest.cc

@@ -4368,6 +4368,29 @@ TEST_F(SplitViewOverviewSessionTest, NoCrashWhenPressTabKey) {
   EXPECT_TRUE(InOverviewSession());
 }
 
+// Tests closing a snapped window while in overview mode.
+TEST_F(SplitViewOverviewSessionTest, ClosingSplitViewWindow) {
+  const gfx::Rect bounds(400, 400);
+  std::unique_ptr<aura::Window> window1(CreateWindow(bounds));
+  std::unique_ptr<aura::Window> window2(CreateWindow(bounds));
+
+  ToggleOverview();
+  // Drag |window1| selector item to snap to left.
+  OverviewItem* overview_item1 =
+      GetOverviewItemInGridWithWindow(0, window1.get());
+  DragWindowTo(overview_item1, gfx::PointF(0, 0));
+  EXPECT_TRUE(overview_controller()->InOverviewSession());
+  EXPECT_TRUE(split_view_controller()->InSplitViewMode());
+
+  // Now close the snapped |window1|. We should remain in overview mode and the
+  // overview focus window should regain focus.
+  window1.reset();
+  EXPECT_TRUE(overview_controller()->InOverviewSession());
+  EXPECT_FALSE(split_view_controller()->InSplitViewMode());
+  EXPECT_EQ(overview_session()->GetOverviewFocusWindow(),
+            window_util::GetFocusedWindow());
+}
+
 // Test the split view and overview functionalities in clamshell mode. Split
 // view is only active when overview is active in clamshell mode.
 class SplitViewOverviewSessionInClamshellTest