Load modules off-main-thread from workers (but not worklets)

Bug: 680046
Change-Id: I46ffe62d8bb9982a717b49b31ed6be7ae62e4baf

TBR=kinuko@chromium.org

Change-Id: I46ffe62d8bb9982a717b49b31ed6be7ae62e4baf
Reviewed-on: https://chromium-review.googlesource.com/1035618
Commit-Queue: Nate Chapin <japhet@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Tsuyoshi Horo <horo@chromium.org>
Reviewed-by: Kouhei Ueno <kouhei@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Reviewed-by: Hiroki Nakagawa <nhiroki@chromium.org>
Cr-Commit-Position: refs/heads/master@{#557707}
34 files changed