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

ash/mus/window_manager.cc

Index: ash/mus/window_manager.cc
diff --git a/ash/mus/window_manager.cc b/ash/mus/window_manager.cc
index 3476cc5f50d21775db6d12b1fa4bf715074796a2..a57620912a70e46555cfb4a0d217019dcc01fec8 100644
--- a/ash/mus/window_manager.cc
+++ b/ash/mus/window_manager.cc
@@ -434,13 +434,15 @@ void WindowManager::OnWmCancelMoveLoop(aura::Window* window) {
     handler->RevertDrag();
 }
 
-ui::mojom::EventResult WindowManager::OnAccelerator(uint32_t id,
-                                                    const ui::Event& event) {
+ui::mojom::EventResult WindowManager::OnAccelerator(
+    uint32_t id,
+    const ui::Event& event,
+    std::unordered_map<std::string, std::vector<uint8_t>>* properties) {
   auto iter = accelerator_handlers_.find(GetAcceleratorNamespaceId(id));
   if (iter == accelerator_handlers_.end())
     return ui::mojom::EventResult::HANDLED;
 
-  return iter->second->OnAccelerator(id, event);
+  return iter->second->OnAccelerator(id, event, properties);
 }
 
 void WindowManager::OnWmSetClientArea(