Converts remaining usage of WmLayoutManager to aura::LayoutManager

ash/wm_window.h

Index: ash/wm_window.h
diff --git a/ash/wm_window.h b/ash/wm_window.h
index de47237a46efe3d3b2dab17d3a7b4a5821bb890f..6483edd168ddc33c25bbfc7111e915dfcdfc3bf0 100644
--- a/ash/wm_window.h
+++ b/ash/wm_window.h
@@ -44,7 +44,6 @@ namespace ash {
 
 class ImmersiveFullscreenController;
 class RootWindowController;
-class WmLayoutManager;
 class WmTransientWindowObserver;
 class WmWindowTestApi;
 enum class WmWindowProperty;
@@ -187,9 +186,6 @@ class ASH_EXPORT WmWindow : public aura::WindowObserver,
   // Moves this to the display where |event| occurred; returns true if moved.
   bool MoveToEventRoot(const ui::Event& event);
 
-  void SetLayoutManager(std::unique_ptr<WmLayoutManager> layout_manager);
-  WmLayoutManager* GetLayoutManager();
-
   // See wm::SetWindowVisibilityChangesAnimated() for details on what this
   // does.
   void SetVisibilityChangesAnimated();