arc: Send cryptohome ID on starting ARC instance.

chromeos/dbus/session_manager_client.cc

Index: chromeos/dbus/session_manager_client.cc
diff --git a/chromeos/dbus/session_manager_client.cc b/chromeos/dbus/session_manager_client.cc
index 9e6f4897e878fd7a92352c0ff215994cba14faa9..d13b1a24b7b11b772e79a1e8da821a73438f0f83 100644
--- a/chromeos/dbus/session_manager_client.cc
+++ b/chromeos/dbus/session_manager_client.cc
@@ -346,12 +346,14 @@ class SessionManagerClientImpl : public SessionManagerClient {
   }
 
   void StartArcInstance(const std::string& socket_path,
+                        const cryptohome::Identification& cryptohome_id,
                         const ArcCallback& callback) override {
     dbus::MethodCall method_call(
         login_manager::kSessionManagerInterface,
         login_manager::kSessionManagerStartArcInstance);
     dbus::MessageWriter writer(&method_call);
     writer.AppendString(socket_path);
+    writer.AppendString(cryptohome_id.id());
     session_manager_proxy_->CallMethod(
         &method_call, dbus::ObjectProxy::TIMEOUT_USE_DEFAULT,
         base::Bind(&SessionManagerClientImpl::OnArcMethod,
@@ -906,6 +908,7 @@ class SessionManagerClientStubImpl : public SessionManagerClient {
   }
 
   void StartArcInstance(const std::string& socket_path,
+                        const cryptohome::Identification& cryptohome_id,
                         const ArcCallback& callback) override {
     callback.Run(false);
   }