Support additional mash shelf alignments.

ash/shelf/shelf_delegate.h

Index: ash/shelf/shelf_delegate.h
diff --git a/ash/shelf/shelf_delegate.h b/ash/shelf/shelf_delegate.h
index 32f08a3aa221b6d50eb3fb7b330a4ae8c0689c75..f4081183b10863da5a1fc6f27e391524d2a525b6 100644
--- a/ash/shelf/shelf_delegate.h
+++ b/ash/shelf/shelf_delegate.h
@@ -7,6 +7,7 @@
 
 #include "ash/ash_export.h"
 #include "ash/shelf/shelf_item_types.h"
+#include "ash/shelf/shelf_types.h"
 
 namespace ash {
 class Shelf;
@@ -21,10 +22,15 @@ class ASH_EXPORT ShelfDelegate {
   // depend on the Shelf being in a known state.
   virtual void OnShelfCreated(Shelf* shelf) = 0;
 
-  // Callback used to inform the delegate that a specific shelf no longer
-  // exists.
+  // Callback used to inform the delegate that a specific shelf was destroyed.
   virtual void OnShelfDestroyed(Shelf* shelf) = 0;
 
+  // Callback used to inform the delegate of alignment changes.
+  virtual void OnAlignmentChanged(ShelfAlignment alignment) = 0;
+
+  // Callback used to inform the delegate of auto-hide behavior changes.
+  virtual void OnAutoHideBehaviorChanged(ShelfAutoHideBehavior auto_hide) = 0;
+
   // Get the shelf ID from an application ID.
   virtual ShelfID GetShelfIDForAppID(const std::string& app_id) = 0;