security_OpenFDs: clarify comment.

BUG=chromium:607632
TEST=None.

Change-Id: I3e6326fb29a90da1f26991502de4e874a5472228
Reviewed-on: https://chromium-review.googlesource.com/354230
Tested-by: Ilja H. Friedel <ihf@chromium.org>
Reviewed-by: Stéphane Marchesin <marcheu@chromium.org>
diff --git a/client/site_tests/security_OpenFDs/security_OpenFDs.py b/client/site_tests/security_OpenFDs/security_OpenFDs.py
index 0d9b363..6598248 100644
--- a/client/site_tests/security_OpenFDs/security_OpenFDs.py
+++ b/client/site_tests/security_OpenFDs/security_OpenFDs.py
@@ -195,8 +195,7 @@
                         # for performance reasons.
                         # See crbug.com/452227.
                         r'0500 /usr/share/fonts/.*',
-                        # TODO(ihf): investigate this transient FD.
-                        # crbug.com/607632.
+                        # Zero-copy texture uploads. crbug.com/607632.
                         r'0700 anon_inode:dmabuf',
                        ])
         try: