Makes WorkspaceLayoutManager use ash/wm/common types

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
index c6ad707d60a74a1e37c140586a7365537b8794ef..7ae244858eec3152bb1273352bfeaa1759a211a6 100644
--- a/ash/wm/common/wm_screen_util.cc
+++ b/ash/wm/common/wm_screen_util.cc
@@ -12,6 +12,10 @@ 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());
 }