Address comments I missed on a previous CL

I accidentally missed some comments on
android-review.googlesource.com/c/305518 when I submitted it. This
addresses those comments.

Test: mma -j40 test-art-host
Change-Id: Icd8ff65dee1730d10489f25e75bddbd455c68413
diff --git a/runtime/mirror/class_ext.cc b/runtime/mirror/class_ext.cc
index 259bbbe..7c6a710 100644
--- a/runtime/mirror/class_ext.cc
+++ b/runtime/mirror/class_ext.cc
@@ -46,8 +46,9 @@
   SetFieldObject<false>(obsolete_methods_off, methods.Ptr());
 }
 
-// TODO We really need to be careful how we update this. If we ever in the future make it so that
-// these arrays are written into without all threads being suspended we have a race condition!
+// We really need to be careful how we update this. If we ever in the future make it so that
+// these arrays are written into without all threads being suspended we have a race condition! This
+// race could cause obsolete methods to be missed.
 bool ClassExt::ExtendObsoleteArrays(Thread* self, uint32_t increase) {
   DCHECK_EQ(GetLockOwnerThreadId(), Thread::Current()->GetThreadId())
       << "Obsolete arrays are set without synchronization!";