ash: Explicitly teach various components about ShelfLayoutManager.

ash/shelf/overflow_bubble_view.h

Index: ash/shelf/overflow_bubble_view.h
diff --git a/ash/shelf/overflow_bubble_view.h b/ash/shelf/overflow_bubble_view.h
index 8859fe2e31cc79eeafb0d1c84ec373523009bfa1..fd31157147e15e90e4a1a4852c154b4b9c627e3b 100644
--- a/ash/shelf/overflow_bubble_view.h
+++ b/ash/shelf/overflow_bubble_view.h
@@ -11,7 +11,6 @@
 #include "ui/views/bubble/bubble_delegate.h"
 
 namespace ash {
-class ShelfLayoutManager;
 class ShelfView;
 
 namespace test {
@@ -52,8 +51,6 @@ class ASH_EXPORT OverflowBubbleView : public views::BubbleDelegateView {
   // ui::EventHandler overrides:
   void OnScrollEvent(ui::ScrollEvent* event) override;
 
-  ShelfLayoutManager* GetShelfLayoutManager() const;
-
   ShelfView* shelf_view_;  // Owned by views hierarchy.
   gfx::Vector2d scroll_offset_;