Tweak a comment.
Tweak a comment.

Change-Id: I1f88baae83bc923d6ac561492cf02e733d76d798
Reviewed-on: https://code-review.googlesource.com/3990
Reviewed-by: Paul Wankadia <62d4e38bb1380f055ec4b899baa75e52af09c5f7@google.com>

google/re2,google/re2,google/re2,google/re2,google/re2