[net] Support opaque origins in split cache.

Prevent resources whose origin is opaque from being cached.
Blink's memory cache should take care of reusing resources
within the current page load, but otherwise a resource with
an opaque top-frame origin won’t be used again.  So if
features::kSplitCacheByTopFrameOrigin is enabled and the
origin is opaque, set HttpCache::Transaction::ShouldPassThrough()
to true.

Bug: 910711
Change-Id: I026cc3adb940e085489f574a9152e07ac3f20e6a
Reviewed-on: https://chromium-review.googlesource.com/c/1423346
Reviewed-by: Shivani Sharma <shivanisha@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Cammie Smith Barnes <cammie@chromium.org>
Cr-Commit-Position: refs/heads/master@{#631302}
3 files changed