Makes WorkspaceLayoutManager use ash/wm/common types

ash/wm/common/wm_screen_util.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 "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/display/display.h"
 
 namespace ash {
 namespace wm {
 
 gfx::Rect GetDisplayWorkAreaBoundsInParent(WmWindow* window) {
+  return GetDisplayWorkAreaBounds(window->GetParent());
+}
+
+gfx::Rect GetDisplayWorkAreaBounds(WmWindow* window) {
   display::Display display = window->GetDisplayNearestWindow();
   return window->GetParent()->ConvertRectFromScreen(display.work_area());
 }
 
 gfx::Rect GetDisplayBoundsInParent(WmWindow* window) {
   display::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