Adds ability for accelerators to add key/value pairs to KeyEvent

ash/mus/accelerators/accelerator_handler.h

Index: ash/mus/accelerators/accelerator_handler.h
diff --git a/ash/mus/accelerators/accelerator_handler.h b/ash/mus/accelerators/accelerator_handler.h
index 87e50a02ac5e1fb82509fe4f53fc59f7b81814a9..089377f2482118d810c122d79d3279b22fdbce4f 100644
--- a/ash/mus/accelerators/accelerator_handler.h
+++ b/ash/mus/accelerators/accelerator_handler.h
@@ -5,6 +5,12 @@
 #ifndef ASH_MUS_ACCELERATORS_ACCELERATOR_HANDLER_H_
 #define ASH_MUS_ACCELERATORS_ACCELERATOR_HANDLER_H_
 
+#include <stdint.h>
+
+#include <string>
+#include <unordered_map>
+#include <vector>
+
 #include "services/ui/public/interfaces/window_manager.mojom.h"
 
 namespace ash {
@@ -13,8 +19,11 @@ namespace mus {
 // Used by WindowManager for handling accelerators.
 class AcceleratorHandler {
  public:
-  virtual ui::mojom::EventResult OnAccelerator(uint32_t id,
-                                               const ui::Event& event) = 0;
+  // See WindowManagerDelegate for details on |properties|.
+  virtual ui::mojom::EventResult OnAccelerator(
+      uint32_t id,
+      const ui::Event& event,
+      std::unordered_map<std::string, std::vector<uint8_t>>* properties) = 0;
 
  protected:
   virtual ~AcceleratorHandler() {}