Make mash register initial batch of accelerators in single shot.

ash/mus/accelerators/accelerator_controller_registrar.h

Index: ash/mus/accelerators/accelerator_controller_registrar.h
diff --git a/ash/mus/accelerators/accelerator_controller_registrar.h b/ash/mus/accelerators/accelerator_controller_registrar.h
index da2841f6979bc5b64bcfcb49f710e495ba346a34..128878094c635c36ca5b77ef4d11d1b5edcd9ad4 100644
--- a/ash/mus/accelerators/accelerator_controller_registrar.h
+++ b/ash/mus/accelerators/accelerator_controller_registrar.h
@@ -8,6 +8,7 @@
 #include <stdint.h>
 
 #include <map>
+#include <vector>
 
 #include "ash/mus/accelerators/accelerator_handler.h"
 #include "base/macros.h"
@@ -42,6 +43,11 @@ class AcceleratorControllerRegistrar : public AcceleratorHandler,
   void OnAcceleratorRegistered(const ui::Accelerator& accelerator) override;
   void OnAcceleratorUnregistered(const ui::Accelerator& accelerator) override;
 
+  void OnAcceleratorsRegistered(
+      std::vector<ui::Accelerator>& accelerators) override;
+  void OnAcceleratorsUnregistered(
+      std::vector<ui::Accelerator>& accelerators) override;
+
  private:
   friend class AcceleratorControllerRegistrarTestApi;
 
@@ -86,6 +92,8 @@ class AcceleratorControllerRegistrar : public AcceleratorHandler,
 
   std::unique_ptr<AcceleratorRouter> router_;
 
+  std::vector<ui::mojom::AcceleratorPtr> accelerator_ptrs_;
+
   // Set of registered local ids.
   std::set<uint16_t> ids_;