Makes ash/mus use RootWindowControllerCommon

ash/mus/fill_layout.cc

Index: ash/mus/fill_layout.cc
diff --git a/ash/mus/fill_layout.cc b/ash/mus/fill_layout.cc
deleted file mode 100644
index 01107d6265c82493251b86dfc8289bfb1c096329..0000000000000000000000000000000000000000
--- a/ash/mus/fill_layout.cc
+++ /dev/null
@@ -1,21 +0,0 @@
-// Copyright 2016 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "ash/mus/fill_layout.h"
-
-#include "components/mus/public/cpp/window.h"
-
-namespace ash {
-namespace mus {
-
-FillLayout::FillLayout(::mus::Window* owner) : LayoutManager(owner) {}
-
-FillLayout::~FillLayout() {}
-
-void FillLayout::LayoutWindow(::mus::Window* window) {
-  window->SetBounds(gfx::Rect(owner()->bounds().size()));
-}
-
-}  // namespace mus
-}  // namespace ash