Remove page_set argument from benchmark.CreateExpectations

Remove page_set argument from benchmark.CreateExpectations to limit the access to page_set (user_story)

BUG=418278
Committed: https://crrev.com/b91e7865b4b62add4e16b5e18becf12316beb0db
Cr-Commit-Position: refs/heads/master@{#297267}

[nednguyen, 2014-09-29 20:12:51]

nednguyen@google.com changed reviewers:
+ kbr@chromium.org, nduca@chromium.org

[dtu, 2014-09-29 20:15:18]

dtu@chromium.org changed reviewers:
+ dtu@chromium.org

[dtu, 2014-09-29 20:15:19]

non-owners lgtm

[nduca, 2014-09-29 20:29:16]

lgtm also

[Ken Russell (switch to Gerrit), 2014-09-29 21:03:56]

lgtm

[nednguyen, 2014-09-29 21:04:45]

The CQ bit was checked by nednguyen@google.com

[commit-bot: I haz the power, 2014-09-29 21:07:29]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/614783002/1

[commit-bot: I haz the power, 2014-09-29 21:16:07]

Committed patchset #1 (id:1) as c321be42033fdbd37f26101a5701ccc54f39e1e1

[commit-bot: I haz the power, 2014-09-29 21:16:56]

Patchset 1 (id:??) landed as
https://crrev.com/b91e7865b4b62add4e16b5e18becf12316beb0db
Cr-Commit-Position: refs/heads/master@{#297267}