[task scheduler] Fix task-sk duration for unfinished tasks
[task scheduler] Fix task-sk duration for unfinished tasks

Bug: skia:
Change-Id: I6c4f0c8a2acd9777fdec3f9cb6c1bcb9fcf70434
Reviewed-on: https://skia-review.googlesource.com/78402
Commit-Queue: Eric Boren <0e499112533c8544f0505ea0d08394fb5ad7d8fa@google.com>
Reviewed-by: Kevin Lubick <7cdab2cfab351f23814786ba39716e90eed69047@google.com>

google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot