chromeos: Remove TrayBubbleView::Delegate::OnBeforeBubbleWidgetInit

ash/system/palette/palette_tray.h

Index: ash/system/palette/palette_tray.h
diff --git a/ash/system/palette/palette_tray.h b/ash/system/palette/palette_tray.h
index b700936ff962e5ab92a5dc33fbcd05355db42d9b..f5aad0c54735a2a48854cdfe8b7ee48f8bcdb10c 100644
--- a/ash/system/palette/palette_tray.h
+++ b/ash/system/palette/palette_tray.h
@@ -23,7 +23,6 @@ class Point;
 
 namespace views {
 class ImageView;
-class Widget;
 }
 
 namespace ash {
@@ -85,10 +84,6 @@ class ASH_EXPORT PaletteTray : public TrayBackgroundView,
   void OnMouseEnteredView() override;
   void OnMouseExitedView() override;
   base::string16 GetAccessibleNameForBubble() override;
-  void OnBeforeBubbleWidgetInit(
-      views::Widget* anchor_widget,
-      views::Widget* bubble_widget,
-      views::Widget::InitParams* params) const override;
   void HideBubble(const views::TrayBubbleView* bubble_view) override;
 
   // PaletteToolManager::Delegate: