Add headers-only component to DiskCachePerfTest.

Add headers-only component to DiskCachePerfTest.

Reading only the headers is a significant gap between SimpleCache and
the blockfile backend. Let's test that independently of reading the
whole bodies.

R=juliatuttle@chromium.org
BUG=611464
Committed: https://crrev.com/dfe07b41c2a19e02c9d8e5e5101c12babe4ca5fe
Cr-Commit-Position: refs/heads/master@{#393595}

[gavinp, 2016-05-12 20:31:21]

Julia: PTAL. Dunno why the tries are all failing? Don't deal with dependant
changes well?

[gavinp, 2016-05-12 20:38:00]

Note: this is downstream of the two other changes I sent out to you this
afternoon. However, it's not showing up properly as a dependent changeset. No
clue here on why, y upload tool claims it is.

*sigh*

[Julia Tuttle, 2016-05-13 16:32:46]

lgtm.

[gavinp, 2016-05-13 18:01:33]

The CQ bit was checked by gavinp@chromium.org

[commit-bot: I haz the power, 2016-05-13 18:02:05]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1976453003/80001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1976453003/80001

[commit-bot: I haz the power, 2016-05-13 19:03:42]

Committed patchset #5 (id:80001)

[commit-bot: I haz the power, 2016-05-13 19:04:40]

Description was changed from

==========
Add headers-only component to DiskCachePerfTest.

Reading only the headers is a significant gap between SimpleCache and
the blockfile backend. Let's test that independently of reading the
whole bodies.

R=juliatuttle@chromium.org
BUG=611464
==========

to

==========
Add headers-only component to DiskCachePerfTest.

Reading only the headers is a significant gap between SimpleCache and
the blockfile backend. Let's test that independently of reading the
whole bodies.

R=juliatuttle@chromium.org
BUG=611464

Committed: https://crrev.com/dfe07b41c2a19e02c9d8e5e5101c12babe4ca5fe
Cr-Commit-Position: refs/heads/master@{#393595}
==========

[commit-bot: I haz the power, 2016-05-13 19:04:41]

Patchset 5 (id:??) landed as
https://crrev.com/dfe07b41c2a19e02c9d8e5e5101c12babe4ca5fe
Cr-Commit-Position: refs/heads/master@{#393595}