Move free disk space check to session_manager.

chromeos/dbus/session_manager_client.h

Index: chromeos/dbus/session_manager_client.h
diff --git a/chromeos/dbus/session_manager_client.h b/chromeos/dbus/session_manager_client.h
index ee142aad64cd384fafa03c44ef9c46683b5c2d7c..aff3d32fbf3b04dba0fc390b92a719a1fc98daba 100644
--- a/chromeos/dbus/session_manager_client.h
+++ b/chromeos/dbus/session_manager_client.h
@@ -233,10 +233,16 @@ class CHROMEOS_EXPORT SessionManagerClient : public DBusClient {
   // blocks Android ACTION_BOOT_COMPLETED broadcast for 3rd party applications.
   // Upon completion, invokes |callback| with the result; true on success, false
   // on failure (either session manager failed to start an instance or session
-  // manager can not be reached).
+  // manager can not be reached). On Failure, the error is passed to the second
+  // argument of the callback. The error may be empty even on failure, if the
+  // reponse is not received at all. The error looks like, e.g.,
+  // "org.freedesktop.DBus.Error.ServiceUnknown".
+  // TODO(hidehiko): Replace "typedef" by "using".
+  typedef base::Callback<void(bool is_succeeded, const std::string& error)>

[hashimoto, 2016/10/06 08:36:59]

nit: "bool success" would be more consistent with existing code.

[hidehiko, 2016/10/06 08:40:22]

Ah, right. Done.

+      StartArcInstanceCallback;
   virtual void StartArcInstance(const cryptohome::Identification& cryptohome_id,
                                 bool disable_boot_completed_broadcast,
-                                const ArcCallback& callback) = 0;
+                                const StartArcInstanceCallback& callback) = 0;
 
   // Asynchronously stops the ARC instance.  Upon completion, invokes
   // |callback| with the result; true on success, false on failure (either