overview: Remove redundant code that unpauses occlusion tracking

There is a part of OverviewItem::OnWindowDestroying that looks exactly
like UnpauseOcclusionTracker from the anonymous namespace in
overview_window_drag_controller.cc. It comes right after calling
OverviewWindowDragController::ResetGesture, which calls
UnpauseOcclusionTracker anyway.

Bug: None
Change-Id: If8070af54b97faf1cb710e7dd06f2395528e13ca
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1898200
Commit-Queue: Avery Musbach <amusbach@chromium.org>
Reviewed-by: Sammie Quon <sammiequon@chromium.org>
Cr-Commit-Position: refs/heads/master@{#712308}

ash/wm/overview/overview_constants.h

@@ -35,11 +35,6 @@ constexpr float kShieldOpacity = 0.4f;
 constexpr float kWallpaperBlurSigma = 10.f;
 constexpr float kWallpaperClearBlurSigma = 0.f;
 
-// Amount of time we wait to unpause the occlusion tracker after a overview item
-// is finished dragging. Waits a bit longer than the overview item animation.
-constexpr base::TimeDelta kOcclusionPauseDurationForDrag =
-    base::TimeDelta::FromMilliseconds(300);
-
 }  // namespace ash
 
 #endif  // ASH_WM_OVERVIEW_OVERVIEW_CONSTANTS_H_

ash/wm/overview/overview_item.cc

@@ -1063,8 +1063,6 @@ void OverviewItem::OnWindowDestroying(aura::Window* window) {
   if (is_being_dragged_) {
     DCHECK_EQ(this, overview_session_->window_drag_controller()->item());
     overview_session_->window_drag_controller()->ResetGesture();
-    Shell::Get()->overview_controller()->UnpauseOcclusionTracker(
-        kOcclusionPauseDurationForDrag);
   }
 
   overview_grid_->RemoveItem(this, /*item_destroying=*/true,

ash/wm/overview/overview_window_drag_controller.cc

@@ -56,6 +56,11 @@ constexpr float kMinimumDragDistanceAlreadyInSnapRegionDp = 48.f;
 constexpr float kFlingToCloseVelocityThreshold = 2000.f;
 constexpr float kItemMinOpacity = 0.4f;
 
+// Amount of time we wait to unpause the occlusion tracker after a overview item
+// is finished dragging. Waits a bit longer than the overview item animation.
+constexpr base::TimeDelta kOcclusionPauseDurationForDrag =
+    base::TimeDelta::FromMilliseconds(300);
+
 // The UMA histogram that records presentation time for window dragging
 // operation in overview mode.
 constexpr char kOverviewWindowDragHistogram[] =