Remove dead code from Benchmark

Spotted the VisualBench hooks the other day, then found some more dead
code when I went to remove them.

Change-Id: Ia07f0556faf33cc69e3ec590f7a8f47f2c1f298a
Reviewed-on: https://skia-review.googlesource.com/146360
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
6 files changed