Introduce HttpStreamFactoryImpl::Job::IsAlternate.

This is refactoring/code cleanup, no functional change intended.  This relies on
the class invariant that (a HttpStreamFactoryImpl::Job instance represents an
alternate job) iff (original_url_ is set) iff (alternative_service_ is
initialized).

Patch Set 1:  Introduce Job::IsAlternate().
Patch Set 2:  Change IsAlternate to rely on |alternative_service_| instead.
Patch Set 3:  Change |orginal_url_| type from scoped_ptr<GURL> to GURL.
Patch Set 4:  Fix typo in ReportJobSucceededForRequest.
Patch Set 5:  s/MaybeMarkAlternateProtocolBroken/MaybeMarkAlternativeServiceBroken/g

BUG=392575

Review URL: https://codereview.chromium.org/1057913003

Cr-Commit-Position: refs/heads/master@{#323736}
3 files changed