mash: Use ash shell window container ids instead of ash::mojom::Container

ash/mus/root_window_controller.h

Index: ash/mus/root_window_controller.h
diff --git a/ash/mus/root_window_controller.h b/ash/mus/root_window_controller.h
index 325a4adcd99b436f5f900e686f9d99b493c83fe5..6fc2a20806d618a9f4508705da337bc14eb433e8 100644
--- a/ash/mus/root_window_controller.h
+++ b/ash/mus/root_window_controller.h
@@ -8,7 +8,6 @@
 #include <memory>
 
 #include "ash/mus/disconnected_app_handler.h"
-#include "ash/public/interfaces/container.mojom.h"
 #include "services/ui/public/cpp/window_observer.h"
 #include "services/ui/public/interfaces/window_manager_constants.mojom.h"
 #include "ui/display/display.h"
@@ -56,8 +55,6 @@ class RootWindowController {
   ui::Window* NewTopLevelWindow(
       std::map<std::string, std::vector<uint8_t>>* properties);
 
-  ui::Window* GetWindowForContainer(mojom::Container container);
-
   WmWindowMus* GetWindowByShellWindowId(int id);
 
   void SetWorkAreaInests(const gfx::Insets& insets);