Worker: Use per-global-scope task runner instead of the default task runner

Bug: 443374
Change-Id: I665874f46c4b4adc829e6a487362b96894d8995e
Reviewed-on: https://chromium-review.googlesource.com/520529
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Tsuyoshi Horo <horo@chromium.org>
Commit-Queue: Hiroki Nakagawa <nhiroki@chromium.org>
Cr-Commit-Position: refs/heads/master@{#476596}
1 file changed