chromeos: convert more ash/wm code to aura::Window

ash/mus/window_manager.cc

Index: ash/mus/window_manager.cc
diff --git a/ash/mus/window_manager.cc b/ash/mus/window_manager.cc
index dbda2e19a80e7a8daf29e4baa0182fea7cf9da1d..b9ea19ffd9acbc2c53ecfacc424a3850b8998d45 100644
--- a/ash/mus/window_manager.cc
+++ b/ash/mus/window_manager.cc
@@ -526,8 +526,7 @@ void WindowManager::OnWmPerformMoveLoop(
     ui::mojom::MoveLoopSource source,
     const gfx::Point& cursor_location,
     const base::Callback<void(bool)>& on_done) {
-  WmWindow* child_window = WmWindow::Get(window);
-  MoveEventHandler* handler = MoveEventHandler::GetForWindow(child_window);
+  MoveEventHandler* handler = MoveEventHandler::GetForWindow(window);
   if (!handler) {
     on_done.Run(false);
     return;
@@ -542,8 +541,7 @@ void WindowManager::OnWmPerformMoveLoop(
 }
 
 void WindowManager::OnWmCancelMoveLoop(aura::Window* window) {
-  WmWindow* child_window = WmWindow::Get(window);
-  MoveEventHandler* handler = MoveEventHandler::GetForWindow(child_window);
+  MoveEventHandler* handler = MoveEventHandler::GetForWindow(window);
   if (handler)
     handler->RevertDrag();
 }