Remove redundant id from Thread.
Remove redundant id from Thread.

Change-Id: I22a7a2f66015e854d87637ada6218df9ed1d2f85
Reviewed-on: https://code-review.googlesource.com/4631
Reviewed-by: Paul Wankadia <62d4e38bb1380f055ec4b899baa75e52af09c5f7@google.com>

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