Adds WmWindow and converts WindowState to use it

ash/wm/common/wm_screen_util.cc

Index: ash/wm/common/wm_screen_util.cc
diff --git a/ash/wm/common/wm_screen_util.cc b/ash/wm/common/wm_screen_util.cc
new file mode 100644
index 0000000000000000000000000000000000000000..dc96aa75fc0361d592782ca3b2826994d1e00f02
--- /dev/null
+++ b/ash/wm/common/wm_screen_util.cc
@@ -0,0 +1,32 @@
+// 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/wm/common/wm_screen_util.h"
+
+#include "ash/wm/common/wm_root_window_controller.h"
+#include "ash/wm/common/wm_window.h"
+#include "ui/gfx/display.h"
+
+namespace ash {
+namespace wm {
+
+gfx::Rect GetDisplayWorkAreaBoundsInParent(WmWindow* window) {
+  gfx::Display display = window->GetDisplayNearestWindow();
+  return window->GetParent()->ConvertRectFromScreen(display.work_area());
+}
+
+gfx::Rect GetDisplayBoundsInParent(WmWindow* window) {
+  gfx::Display display = window->GetDisplayNearestWindow();
+  return window->GetParent()->ConvertRectFromScreen(display.bounds());
+}
+
+gfx::Rect GetMaximizedWindowBoundsInParent(WmWindow* window) {
+  if (window->GetRootWindowController()->HasShelf())
+    return GetDisplayWorkAreaBoundsInParent(window);
+
+  return GetDisplayBoundsInParent(window);
+}
+
+}  // namespace wm
+}  // namespace ash