Add LockLayoutManager responsible for lock container (login/lock).

ash/wm/window_state.h

Index: ash/wm/window_state.h
diff --git a/ash/wm/window_state.h b/ash/wm/window_state.h
index 4ce47fdd275de07c806862b87139820d1d12b208..91496fec5be5e87caea59040a11214206d4875c6 100644
--- a/ash/wm/window_state.h
+++ b/ash/wm/window_state.h
@@ -25,6 +25,7 @@ class Rect;
 
 namespace ash {
 class WorkspaceLayoutManager;
+class LockWindowState;
 class MaximizeModeWindowState;
 
 namespace wm {
@@ -292,6 +293,7 @@ class ASH_EXPORT WindowState : public aura::WindowObserver {
 
  private:
   friend class DefaultState;
+  friend class ash::LockWindowState;
   friend class ash::MaximizeModeWindowState;
   FRIEND_TEST_ALL_PREFIXES(WindowAnimationsTest, CrossFadeToBounds);