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 5683eae7599626b233a33ec1fb28fcd68f32efef..22e0ccb8b855c9d6ea85b4d40d4cab310fe36828 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: