Fixes shutdown race in mash

ash/mus/accelerator_registrar_impl.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef ASH_MUS_ACCELERATOR_REGISTRAR_IMPL_H_
 #define ASH_MUS_ACCELERATOR_REGISTRAR_IMPL_H_
 
 #include <stdint.h>
 
 #include <map>
 
+#include "ash/mus/window_manager_observer.h"
 #include "base/callback.h"
 #include "base/macros.h"
 #include "components/mus/public/interfaces/accelerator_registrar.mojom.h"
 #include "mojo/public/cpp/bindings/binding_set.h"
 #include "mojo/public/cpp/bindings/strong_binding.h"
 
 namespace ash {
 namespace mus {
 
 class WindowManager;
 
 // Manages AcceleratorHandlers from a particular AcceleratorRegistrar
 // connection. This manages its own lifetime, and destroys itself when the
 // AcceleratorRegistrar and all its AcceleratorHandlers are disconnected. Upon
 // destruction, it calls the DestroyCallback.
-class AcceleratorRegistrarImpl : public ::mus::mojom::AcceleratorRegistrar {
+class AcceleratorRegistrarImpl : public ::mus::mojom::AcceleratorRegistrar,
+                                 public WindowManagerObserver {
  public:
   using DestroyCallback = base::Callback<void(AcceleratorRegistrarImpl*)>;
   AcceleratorRegistrarImpl(WindowManager* window_manager,
                            uint32_t accelerator_namespace,
                            mojo::InterfaceRequest<AcceleratorRegistrar> request,
                            const DestroyCallback& destroy_callback);
 
   void Destroy();
 
   // Returns true if this AcceleratorRegistrar has an accelerator with the
@@ skipping 11 matching lines @@
 
   void RemoveAllAccelerators();
 
   // ::mus::mojom::AcceleratorRegistrar:
   void SetHandler(::mus::mojom::AcceleratorHandlerPtr handler) override;
   void AddAccelerator(uint32_t accelerator_id,
                       ::mus::mojom::EventMatcherPtr matcher,
                       const AddAcceleratorCallback& callback) override;
   void RemoveAccelerator(uint32_t accelerator_id) override;
 
+  // WindowManagerObserver:
+  void OnAccelerator(uint32_t id, const ui::Event& event) override;
+  void OnWindowTreeClientDestroyed() override;
+
   WindowManager* window_manager_;
   ::mus::mojom::AcceleratorHandlerPtr accelerator_handler_;
   mojo::Binding<AcceleratorRegistrar> binding_;
   uint32_t accelerator_namespace_;
   std::set<uint32_t> accelerators_;
   DestroyCallback destroy_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(AcceleratorRegistrarImpl);
 };
 
 }  // namespace mus
 }  // namespace ash
 
 #endif  // ASH_MUS_ACCELERATOR_REGISTRAR_IMPL_H_