Converts RootWindowLayoutManager to common types

ash/test/shell_test_api.cc

Index: ash/test/shell_test_api.cc
diff --git a/ash/test/shell_test_api.cc b/ash/test/shell_test_api.cc
index b042e476973741c106598bb7093467bbd8c926c5..b8ecbe56354979ebf82828402d2b214fa9c5cc50 100644
--- a/ash/test/shell_test_api.cc
+++ b/ash/test/shell_test_api.cc
@@ -16,10 +16,6 @@ namespace test {
 
 ShellTestApi::ShellTestApi(Shell* shell) : shell_(shell) {}
 
-RootWindowLayoutManager* ShellTestApi::root_window_layout() {
-  return shell_->GetPrimaryRootWindowController()->root_window_layout();
-}
-
 SystemGestureEventFilter* ShellTestApi::system_gesture_event_filter() {
   return shell_->system_gesture_filter_.get();
 }