Evict "fallback" RawResource from MemoryCache

A service worker may ask the original renderer to re-fetch the request when a
fetch-mode=CORS request was not handled. In most cases ResourceLoader restarts
the resource, but in some cases it lets DocumentThreadableLoader handle the
response. In such a case, we can see a Resource whose response's
WasFallbackRequiredByServiceWorker is true.

Previously ResourceFetcher::DetermineRevalidationPolicy forbade to reuse such
a resource. This CL removes the logic. Instead, RawResource evicts itself when
receiving such a response.

BUG=652228
R=horo@chromium.org, tyoshino@chromium.org

Review-Url: https://codereview.chromium.org/2830753003
Cr-Commit-Position: refs/heads/master@{#465987}
2 files changed