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

mash/webtest/webtest.h

Index: mash/webtest/webtest.h
diff --git a/mash/webtest/webtest.h b/mash/webtest/webtest.h
index 3a54053a22769cbbcdc6892086fef8b8ce00ad55..d5012e374d1d7ad43c1070ad5847b417328d9177 100644
--- a/mash/webtest/webtest.h
+++ b/mash/webtest/webtest.h
@@ -13,6 +13,10 @@
 #include "services/service_manager/public/cpp/interface_factory.h"
 #include "services/service_manager/public/cpp/service.h"
 #include "services/tracing/public/cpp/provider.h"
+
+namespace service_manager {
+class ServiceContext;
+}
 
 namespace views {
 class AuraInit;
@@ -35,7 +39,7 @@
 
  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;
 
@@ -45,6 +49,8 @@
   // service_manager::InterfaceFactory<mojom::Launchable>:
   void Create(const service_manager::Identity& remote_identity,
               mojom::LaunchableRequest request) override;
+
+  service_manager::ServiceContext* context_ = nullptr;
 
   mojo::BindingSet<mojom::Launchable> bindings_;
   std::vector<views::Widget*> windows_;