[ash] Add TYPE_DIALOG and its item's LauncherContextMenu

ash/shelf/shelf_item_delegate.h

Index: ash/shelf/shelf_item_delegate.h
diff --git a/ash/shelf/shelf_item_delegate.h b/ash/shelf/shelf_item_delegate.h
index 72815cf80f6eae6f507c7de79e68b200dff566ba..6ac81b3c0d4ac2ed11c89746004ce8add84578e3 100644
--- a/ash/shelf/shelf_item_delegate.h
+++ b/ash/shelf/shelf_item_delegate.h
@@ -59,6 +59,10 @@ class ASH_EXPORT ShelfItemDelegate {
 
   // Returns true if a tooltip should be shown.
   virtual bool ShouldShowTooltip() = 0;
+
+  // Closes all windows associated with this item.
+  virtual void Close() = 0;
+
 };
 
 }  // namespace ash