Revert of Service Manager: Remove ServiceContext* arg from Service::OnStart()

mash/init/init.h

Index: mash/init/init.h
diff --git a/mash/init/init.h b/mash/init/init.h
index 71782d256aaef3d81ccf456e0e504dbc3a0d298b..e1987a9b6aceee26d8a723cd30d59915be7b568b 100644
--- a/mash/init/init.h
+++ b/mash/init/init.h
@@ -18,6 +18,7 @@
 
 namespace service_manager {
 class Connection;
+class ServiceContext;
 }
 
 namespace mash {
@@ -32,7 +33,7 @@
 
  private:
   // service_manager::Service:
-  void OnStart() override;
+  void OnStart(service_manager::ServiceContext* context) override;
   bool OnConnect(const service_manager::ServiceInfo& remote_info,
                  service_manager::InterfaceRegistry* registry) override;
 
@@ -50,6 +51,8 @@
   void StartTracing();
   void StartLogin();
 
+  service_manager::ServiceContext* context_ = nullptr;
+
   std::unique_ptr<service_manager::Connection> login_connection_;
   mojo::BindingSet<mojom::Init> init_bindings_;
   std::map<std::string, std::unique_ptr<service_manager::Connection>>