Add simplistic screenlock application.

mash/wm/screenlock_layout.cc

+// 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 "mash/wm/screenlock_layout.h"
+
+#include "components/mus/public/cpp/property_type_converters.h"
+#include "components/mus/public/cpp/window.h"
+#include "components/mus/public/cpp/window_property.h"
+#include "mash/wm/property_util.h"
+#include "ui/gfx/geometry/rect.h"
+
+namespace mash {
+namespace wm {
+
+ScreenlockLayout::ScreenlockLayout(mus::Window* owner) : LayoutManager(owner) {}
+ScreenlockLayout::~ScreenlockLayout() {}
+
+// We explicitly don't make assertions about the number of children in this
+// layout as the number of children can vary when the application providing the
+// screenlock restarts.
+
+void ScreenlockLayout::LayoutWindow(mus::Window* window) {
+  window->SetBounds(owner()->bounds());
+}
+
+}  // namespace wm
+}  // namespace mash