Roll external/skia 68d1879c9..b40902b6b (1 commits)

https://skia.googlesource.com/skia.git/+log/68d1879c9..b40902b6b

2017-08-15 kjlubick@google.com Add upload to task name schema file

Test: Presubmit checks will test this change.
Change-Id: I2f26e5656b3f8eb400b3abadba0fe25176454618