[AppCache] ReportBadMessage rather than DCHECK for first_party_url_ check.

If first_party_url_ hasn't been initialized when SelectCache is called it
means the renderer is somehow trying to select a Cache for a main resource
that was never actually fetched. That is only possible if the renderer is
misbehaving, so return false to trigger a mojo::ReportBadMessage.

Bug: 917827
Change-Id: I9c02a6ea4ea328c736f24cf2b2666363192de03f
Reviewed-on: https://chromium-review.googlesource.com/c/1407910
Commit-Queue: Marijn Kruisselbrink <mek@chromium.org>
Commit-Queue: Victor Costan <pwnall@chromium.org>
Reviewed-by: Victor Costan <pwnall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#622250}
2 files changed