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

mash/session/session.h

Index: mash/session/session.h
diff --git a/mash/session/session.h b/mash/session/session.h
index 211387332757bece569bbe2760bf24ce3a8da958..576492b102c1668fe2e33a710e3e8665b6c6e348 100644
--- a/mash/session/session.h
+++ b/mash/session/session.h
@@ -18,7 +18,6 @@
 
 namespace service_manager {
 class Connection;
-class ServiceContext;
 }
 
 namespace mash {
@@ -33,7 +32,7 @@ class Session : public service_manager::Service,
 
  private:
   // service_manager::Service:
-  void OnStart(service_manager::ServiceContext* context) override;
+  void OnStart() override;
   bool OnConnect(const service_manager::ServiceInfo& remote_info,
                  service_manager::InterfaceRegistry* registry) override;
 
@@ -60,8 +59,6 @@ class Session : public service_manager::Service,
   void StartRestartableService(const std::string& url,
                                const base::Closure& restart_callback);
 
-  service_manager::ServiceContext* context_ = nullptr;
-
   std::map<std::string, std::unique_ptr<service_manager::Connection>>
       connections_;
   bool screen_locked_;