Fix a crash in HttpVaryData::MatchesRequests.

Fix a crash in HttpVaryData::MatchesRequests.

crbug.com/469675 remove an implicit Vary: Cookie for redirected
requests. But some cached redirected requests could still have
HttpVaryData::is_valid_ == true.

Therefore some requests could reach a NOTREACHED() in
HttpVaryData::MatchesRequests() because comparing an HTTP request
vary that have a HttpVaryData::Init() now returning false because
no Vary from the request with a previously cached HttpVaryRequest
that have is_valid_ == true.

BUG=611575
Review-Url: https://codereview.chromium.org/2000123002
Cr-Commit-Position: refs/heads/master@{#395317}
(cherry picked from commit 7ec544a858f4dd2b5b3a0ad0949a1f24f55f10b4)

Committed: https://chromium.googlesource.com/chromium/src/+/ac453e0ec84fd9f1c87bf06080eca3a586f32bee

[gavinp, 2016-05-24 14:29:10]

Description was changed from

==========
Fix a crash in HttpVaryData::MatchesRequests.

crbug.com/469675 remove an implicit Vary: Cookie for redirected
requests. But some cached redirected requests could still have
HttpVaryData::is_valid_ == true.

Therefore some requests could reach a NOTREACHED() in
HttpVaryData::MatchesRequests() because comparing an HTTP request
vary that have a HttpVaryData::Init() now returning false because
no Vary from the request with a previously cached HttpVaryRequest
that have is_valid_ == true.

BUG=611575

Review-Url: https://codereview.chromium.org/2000123002
Cr-Commit-Position: refs/heads/master@{#395317}
(cherry picked from commit 7ec544a858f4dd2b5b3a0ad0949a1f24f55f10b4)
==========

to

==========
Fix a crash in HttpVaryData::MatchesRequests.

crbug.com/469675 remove an implicit Vary: Cookie for redirected
requests. But some cached redirected requests could still have
HttpVaryData::is_valid_ == true.

Therefore some requests could reach a NOTREACHED() in
HttpVaryData::MatchesRequests() because comparing an HTTP request
vary that have a HttpVaryData::Init() now returning false because
no Vary from the request with a previously cached HttpVaryRequest
that have is_valid_ == true.

BUG=611575

Review-Url: https://codereview.chromium.org/2000123002
Cr-Commit-Position: refs/heads/master@{#395317}
(cherry picked from commit 7ec544a858f4dd2b5b3a0ad0949a1f24f55f10b4)

Committed:
https://chromium.googlesource.com/chromium/src/+/ac453e0ec84fd9f1c87bf06080ec...
==========

[gavinp, 2016-05-24 14:29:13]

Committed patchset #1 (id:1) manually as
ac453e0ec84fd9f1c87bf06080eca3a586f32bee.