Remove WorkerFetchContext::Create

Bug: 880027
Change-Id: I56241a02b5900188582c83aa0b6560304e6e165f
Reviewed-on: https://chromium-review.googlesource.com/c/1379052
Commit-Queue: Hiroshige Hayashizaki <hiroshige@chromium.org>
Reviewed-by: Hiroki Nakagawa <nhiroki@chromium.org>
Cr-Commit-Position: refs/heads/master@{#617764}
3 files changed