Makes WorkspaceLayoutManager use ash/wm/common types

ash/wm/aura/wm_root_window_controller_aura.cc

Index: ash/wm/aura/wm_root_window_controller_aura.cc
diff --git a/ash/wm/aura/wm_root_window_controller_aura.cc b/ash/wm/aura/wm_root_window_controller_aura.cc
index 9d5d8333cc591df6b998dcd49e27a3bbca5017d8..ed6f18ccc1f8089df734e6a81030adb0f42fa9c2 100644
--- a/ash/wm/aura/wm_root_window_controller_aura.cc
+++ b/ash/wm/aura/wm_root_window_controller_aura.cc
@@ -79,6 +79,10 @@ WorkspaceWindowState WmRootWindowControllerAura::GetWorkspaceWindowState() {
   return root_window_controller_->workspace_controller()->GetWindowState();
 }
 
+AlwaysOnTopController* WmRootWindowControllerAura::GetAlwaysOnTopController() {
+  return root_window_controller_->always_on_top_controller();
+}
+
 WmShelf* WmRootWindowControllerAura::GetShelf() {
   return root_window_controller_->shelf()
              ? root_window_controller_->shelf()->shelf()->wm_shelf()