Add a GPU calmbench bot

Bug: skia:
Change-Id: I354c295ce04f5e478e88f724e0b17ce90496a4cc
Reviewed-on: https://skia-review.googlesource.com/65341
Commit-Queue: Yuqian Li <liyuqian@google.com>
Reviewed-by: Eric Boren <borenet@google.com>
13 files changed