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..5feeeed84af51ccdc487d02fb028c82197b53ffb 100644
--- a/ash/shelf/overflow_bubble_view.h
+++ b/ash/shelf/overflow_bubble_view.h
@@ -43,6 +43,8 @@ class ASH_EXPORT OverflowBubbleView : public views::BubbleDelegateView {
   void ScrollByXOffset(int x_offset);
   void ScrollByYOffset(int y_offset);
 
+  ShelfLayoutManager* GetShelfLayoutManager() const;
+
   // views::View overrides:
   gfx::Size GetPreferredSize() const override;
   void Layout() override;
@@ -52,8 +54,6 @@ 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_;