mus: Add debug key to print the server window hierarchy

components/mus/ws/window_manager_state.h

Index: components/mus/ws/window_manager_state.h
diff --git a/components/mus/ws/window_manager_state.h b/components/mus/ws/window_manager_state.h
index 574ecd8d2540240bbd617ce154f635a1276bfc6a..fa0311d5fd14a5e4f4abacf3921fad3ae10d3dff 100644
--- a/components/mus/ws/window_manager_state.h
+++ b/components/mus/ws/window_manager_state.h
@@ -150,6 +150,12 @@ class WindowManagerState : public EventDispatcherDelegate {
                                       const ui::Event& event,
                                       base::WeakPtr<Accelerator> accelerator);
 
+  // Registers accelerators used internally for debugging.
+  void AddDebugAccelerators();
+
+  // Returns true if the accelerator was handled.
+  bool HandleDebugAccelerator(uint32_t accelerator_id);
+
   // EventDispatcherDelegate:
   void OnAccelerator(uint32_t accelerator_id, const ui::Event& event) override;
   void SetFocusedWindowFromEventDispatcher(ServerWindow* window) override;