mash: Fix crash when clicking on the shelf overflow icon

ash/system/tray/tray_background_view.cc

Index: ash/system/tray/tray_background_view.cc
diff --git a/ash/system/tray/tray_background_view.cc b/ash/system/tray/tray_background_view.cc
index 56f20f78fff14f7073bb381db7426afbcecafa29..1f2cf2628582753c3e73b8a86ab5d18a1b8b71ab 100644
--- a/ash/system/tray/tray_background_view.cc
+++ b/ash/system/tray/tray_background_view.cc
@@ -265,6 +265,17 @@ void TrayBackgroundView::Initialize() {
   SetTrayBorder();
 }
 
+// static
+void TrayBackgroundView::InitializeBubbleAnimations(
+    views::Widget* bubble_widget) {
+  aura::Window* window = bubble_widget->GetNativeWindow();
+  ::wm::SetWindowVisibilityAnimationType(
+      window, ::wm::WINDOW_VISIBILITY_ANIMATION_TYPE_FADE);
+  ::wm::SetWindowVisibilityAnimationTransition(window, ::wm::ANIMATE_HIDE);
+  ::wm::SetWindowVisibilityAnimationDuration(
+      window, base::TimeDelta::FromMilliseconds(kAnimationDurationForPopupMs));
+}
+
 void TrayBackgroundView::SetVisible(bool visible) {
   if (visible == layer()->GetTargetVisibility())
     return;
@@ -459,18 +470,6 @@ void TrayBackgroundView::HideTransformation() {
   layer()->SetTransform(transform);
 }
 
-void TrayBackgroundView::InitializeBubbleAnimations(
-    views::Widget* bubble_widget) {
-  ::wm::SetWindowVisibilityAnimationType(
-      bubble_widget->GetNativeWindow(),
-      ::wm::WINDOW_VISIBILITY_ANIMATION_TYPE_FADE);
-  ::wm::SetWindowVisibilityAnimationTransition(bubble_widget->GetNativeWindow(),
-                                               ::wm::ANIMATE_HIDE);
-  ::wm::SetWindowVisibilityAnimationDuration(
-      bubble_widget->GetNativeWindow(),
-      base::TimeDelta::FromMilliseconds(kAnimationDurationForPopupMs));
-}
-
 aura::Window* TrayBackgroundView::GetBubbleWindowContainer() const {
   return ash::Shell::GetContainer(
       tray_container()->GetWidget()->GetNativeWindow()->GetRootWindow(),