Fix overloaded pipeline integration tests to support underflow.

Fix overloaded pipeline integration tests to support underflow.

Also disables the hash tests which seem to be flaking on the bots.
I was not able to reproduce this flake locally under valgrind.

BUG=492882, 496466
TEST=all pipeline tests pass under valgrind.

Committed: https://crrev.com/11d2b2085216156e3cc10c0b701e5582332a52a0
Cr-Commit-Position: refs/heads/master@{#333181}

[DaleCurtis, 2015-06-05 21:57:00]

dalecurtis@chromium.org changed reviewers:
+ xhwang@chromium.org

[xhwang, 2015-06-05 21:59:43]

lgtm

[DaleCurtis, 2015-06-05 23:38:05]

The CQ bit was checked by dalecurtis@chromium.org

[commit-bot: I haz the power, 2015-06-05 23:39:15]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1152803003/1

[commit-bot: I haz the power, 2015-06-06 00:06:01]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-06-06 00:06:44]

Patchset 1 (id:??) landed as
https://crrev.com/11d2b2085216156e3cc10c0b701e5582332a52a0
Cr-Commit-Position: refs/heads/master@{#333181}