[Telemetry] Add Chris Henry to core Telemetry OWNERS.

BUG=
NOTRY=True

Review URL: https://codereview.chromium.org/493143002

Cr-Commit-Position: refs/heads/master@{#291105}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@291105 0039d316-1c4b-4281-b951-d872f2087c98

tools/telemetry/OWNERS

@@ -7,6 +7,7 @@ set noparent
 # For CrOS-related changes.
 achuith@chromium.org
 
+chrishenry@google.com
 dtu@chromium.org
 ernstm@chromium.org
 marja@chromium.org