cros: Reset overview item header clipping when moving displays.

Currently if a user moves a window to another display via overview, its
header is invisible upon exiting overview.

This CL resets the clipping created when the overview item is created
to prevent this bug.

Test: manual
Fixed: 1140639
Change-Id: I9e5d943bcb4ac7e8fb2054775c2695b2516dc381
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2533553
Commit-Queue: Jeremy Chinsen <chinsenj@chromium.org>
Reviewed-by: Sammie Quon <sammiequon@chromium.org>
Cr-Commit-Position: refs/heads/master@{#826865}

ash/wm/overview/scoped_overview_transform_window.cc

@@ -215,6 +215,12 @@ ScopedOverviewTransformWindow::ScopedOverviewTransformWindow(
 }
 
 ScopedOverviewTransformWindow::~ScopedOverviewTransformWindow() {
+  // Reset clipping in the case RestoreWindow() is not called, such as when
+  // |this| is dragged to another display. This is a no-op if SetClipping() was
+  // called in RestoreWindow().
+  // See crbug.com/1140639.
+  SetClipping({ClippingType::kExit, gfx::SizeF()});
+
   for (auto* transient : GetTransientTreeIterator(window_)) {
     transient->ClearProperty(chromeos::kIsShowingInOverviewKey);
     DCHECK(event_targeting_blocker_map_.contains(transient));