mash: Preliminary support for shelf auto-hide

ash/shell/shelf_delegate_impl.cc

Index: ash/shell/shelf_delegate_impl.cc
diff --git a/ash/shell/shelf_delegate_impl.cc b/ash/shell/shelf_delegate_impl.cc
index 48e7e3be522b3071827aae1fe0c862e0c4375b68..53fdf4d7f7de4fef91b22265f6cdc29edb50c7ca 100644
--- a/ash/shell/shelf_delegate_impl.cc
+++ b/ash/shell/shelf_delegate_impl.cc
@@ -21,6 +21,10 @@ void ShelfDelegateImpl::OnShelfAlignmentChanged(Shelf* shelf) {}
 
 void ShelfDelegateImpl::OnShelfAutoHideBehaviorChanged(Shelf* shelf) {}
 
+void ShelfDelegateImpl::OnShelfAutoHideStateChanged(Shelf* shelf) {}
+
+void ShelfDelegateImpl::OnShelfVisibilityStateChanged(Shelf* shelf) {}
+
 ShelfID ShelfDelegateImpl::GetShelfIDForAppID(const std::string& app_id) {
   return 0;
 }