Reland "Ash Tray: Fix quick settings not closing after clicking on a notification."

This is a reland of b622130a

Original change's description:
> Ash Tray: Fix quick settings not closing after clicking on a notification.
> 
> BUG=1024100
> 
> Change-Id: Ib30e43689842069e4647f7f455a919c62a3c7844
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1928042
> Reviewed-by: Ahmed Mehfooz <amehfooz@chromium.org>
> Commit-Queue: Ahmed Mehfooz <amehfooz@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#717775}

Bug: 1024100
Change-Id: Ie4e4435f0b336b77e856705512a21911704a95b8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1962799Reviewed-by: Ahmed Mehfooz <amehfooz@chromium.org>
Commit-Queue: Ahmed Mehfooz <amehfooz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#725204}

ash/system/unified/unified_system_tray_bubble.cc

@@ -303,17 +303,13 @@ void UnifiedSystemTrayBubble::OnWindowActivated(ActivationReason reason,
     return;
   }
 
-  // Don't close the bubble if the message center is gaining or losing
-  // activation.
+  // Don't close the bubble if the message center is gaining activation.
   if (features::IsUnifiedMessageCenterRefactorEnabled() &&
       tray_->IsMessageCenterBubbleShown()) {
     views::Widget* message_center_widget =
         tray_->message_center_bubble()->GetBubbleWidget();
     if (message_center_widget ==
-            views::Widget::GetWidgetForNativeView(gained_active) ||
-        (lost_active &&
-         message_center_widget ==
-             views::Widget::GetWidgetForNativeView(lost_active))) {
+        views::Widget::GetWidgetForNativeView(gained_active)) {
       return;
     }
   }