Remove FetchContext::ApplicationCacheHostId

Bug: 914739
Change-Id: I8575979a29159821e187ebf3476e181fc5e1197b
Reviewed-on: https://chromium-review.googlesource.com/c/1388353
Commit-Queue: Yutaka Hirano <yhirano@chromium.org>
Reviewed-by: Hiroki Nakagawa <nhiroki@chromium.org>
Cr-Commit-Position: refs/heads/master@{#618506}
7 files changed