shill: Cleanup - private callback methods shouldn't be virtual.

Fix a not-quite-correct comment while here.

BUG=None
TEST=compilation, unit tests pass. No functional change intended.

Change-Id: Iacf194c3aed49db25103685f5a373344a5820379
Reviewed-on: https://gerrit.chromium.org/gerrit/20638
Tested-by: Nathan J. Williams <njw@chromium.org>
Reviewed-by: mukesh agrawal <quiche@chromium.org>
Reviewed-by: Jason Glasgow <jglasgow@chromium.org>
Commit-Ready: Jason Glasgow <jglasgow@chromium.org>
diff --git a/cellular.cc b/cellular.cc
index 94ad672..e820d4d 100644
--- a/cellular.cc
+++ b/cellular.cc
@@ -337,8 +337,7 @@
   capability_->SetupConnectProperties(&properties);
   service_->SetState(Service::kStateAssociating);
   // TODO(njw): Should a weak pointer be used here instead?
-  // Would require something like a WeakPtrFactory on the class,
-  // and the Classic and Universal subclasses already have one.
+  // Would require something like a WeakPtrFactory on the class.
   ResultCallback cb = Bind(&Cellular::OnConnectReply, this);
   capability_->Connect(properties, error, cb);
 }