overview: Update grid bounds when dragged window is deleted.

Test: manual, added test
Change-Id: Id7b6cf15b0efcbfcf714f63146c99695956d4e0a
Fixed: 1020343
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1898748Reviewed-by: Avery Musbach <amusbach@chromium.org>
Reviewed-by: Xiaoqian Dai <xdai@chromium.org>
Commit-Queue: Sammie Quon <sammiequon@chromium.org>
Cr-Commit-Position: refs/heads/master@{#712757}

ash/wm/overview/overview_grid.cc

@@ -661,8 +661,26 @@ void OverviewGrid::RemoveItem(OverviewItem* overview_item,
     return;
   }
 
-  if (reposition)
-    PositionWindows(/*animate=*/true);
+  if (reposition) {
+    // Update the grid bounds if needed and reposition the windows minus the
+    // currently overview dragged window, if there is one. Note: this does not
+    // update the grid bounds if the window being dragged from the top or shelf,
+    // the former being handled in TabletModeWindowDragDelegate's destructor.
+    base::flat_set<OverviewItem*> ignored_items;
+    if (overview_session_->window_drag_controller() &&
+        overview_session_->window_drag_controller()->item()) {
+      ignored_items.insert(overview_session_->window_drag_controller()->item());
+    }
+    auto* split_view_drag_indicators =
+        overview_session_->split_view_drag_indicators();
+    const gfx::Rect grid_bounds = GetGridBoundsInScreenForSplitview(
+        root_window_,
+        split_view_drag_indicators
+            ? base::make_optional(
+                  split_view_drag_indicators->current_window_dragging_state())
+            : base::nullopt);
+    SetBoundsAndUpdatePositions(grid_bounds, ignored_items, /*animate=*/true);
+  }
 }
 
 void OverviewGrid::AddDropTargetForDraggingFromOverview(

ash/wm/overview/overview_session_unittest.cc

@@ -5201,6 +5201,31 @@ TEST_P(SplitViewOverviewSessionTest,
   EXPECT_FALSE(overview_item->IsDragItem());
 }
 
+// Tests that a window which is dragged to a splitview zone is destroyed, the
+// grid bounds return to a non-splitview bounds.
+TEST_P(SplitViewOverviewSessionTest, GridBoundsAfterWindowDestroyed) {
+  // Create two windows otherwise we exit overview after one window is
+  // destroyed.
+  std::unique_ptr<aura::Window> window1 = CreateTestWindow();
+  std::unique_ptr<aura::Window> window2 = CreateTestWindow();
+
+  ToggleOverview();
+  const gfx::Rect grid_bounds = GetGridBounds();
+  // Drag the item such that the splitview preview area shows up and the grid
+  // bounds shrink.
+  OverviewItem* overview_item = GetOverviewItemForWindow(window1.get());
+  overview_session()->InitiateDrag(overview_item,
+                                   overview_item->target_bounds().CenterPoint(),
+                                   /*is_touch_dragging=*/true);
+  overview_session()->Drag(overview_item, gfx::PointF(1.f, 1.f));
+  EXPECT_NE(grid_bounds, GetGridBounds());
+
+  // Tests that when the dragged window is destroyed, the grid bounds return to
+  // their normal size.
+  window1.reset();
+  EXPECT_EQ(grid_bounds, GetGridBounds());
+}
+
 // Test the split view and overview functionalities in clamshell mode. Split
 // view is only active when overview is active in clamshell mode.
 class SplitViewOverviewSessionInClamshellTest

ash/wm/tablet_mode/tablet_mode_window_drag_delegate.cc

@@ -105,7 +105,10 @@ TabletModeWindowDragDelegate::~TabletModeWindowDragDelegate() {
     OverviewGrid* overview_grid = GetOverviewGrid(dragged_window_);
     if (overview_grid) {
       overview_grid->RemoveDropTarget();
-      overview_grid->PositionWindows(/*animate=*/true);
+      const gfx::Rect grid_bounds =
+          GetGridBoundsInScreenForSplitview(dragged_window_, base::nullopt);
+      overview_grid->SetBoundsAndUpdatePositions(
+          grid_bounds, /*ignored_items=*/{}, /*animate=*/true);
     }
   }