mash: Create and show a shelf in mash.

ash/shelf/shelf.h

Index: ash/shelf/shelf.h
diff --git a/ash/shelf/shelf.h b/ash/shelf/shelf.h
index 696a8f903825bea84601e5dbea6f903939c9d07e..4a244d597f07f4c098fd1d43d06cc741a1972a14 100644
--- a/ash/shelf/shelf.h
+++ b/ash/shelf/shelf.h
@@ -34,7 +34,6 @@ namespace ash {
 class AppListButton;
 class FocusCycler;
 class ShelfDelegate;
-class ShelfIconObserver;
 class ShelfView;
 class WmShelf;
 
@@ -90,9 +89,6 @@ class ASH_EXPORT Shelf {
   // Cycles the window focus linearly over the current shelf items.
   void CycleWindowLinear(CycleDirection direction);
 
-  void AddIconObserver(ShelfIconObserver* observer);
-  void RemoveIconObserver(ShelfIconObserver* observer);
-
   // Returns true if the shelf is showing a context menu.
   bool IsShowingMenu() const;