Move PageTest.ValidatePageSet special-case into profile creator.

Move PageTest.ValidatePageSet special-case into profile creator.

PageTest and user_story_runner.Run do not need to touch this method
because it only has to do with a profile creator case.

BUG=440101
Committed: https://crrev.com/4a1bf1ab11f7e5a59a55aac9f45bc60b81e58b73
Cr-Commit-Position: refs/heads/master@{#319521}

[slamm, 2015-03-06 00:24:55]

slamm@chromium.org changed reviewers:
+ erikchen@chromium.org, nednguyen@google.com

[nednguyen, 2015-03-06 00:28:23]

nednguyen@google.com changed reviewers:
+ aiolos@chromium.org

[erikchen, 2015-03-06 00:47:18]

lgtm

[nednguyen, 2015-03-06 02:23:02]

lgtm if both Erik & Kari are happy

[aiolos (Not reviewing), 2015-03-06 02:25:40]

On 2015/03/06 02:23:02, nednguyen wrote:
> lgtm if both Erik & Kari are happy

lgtm

[slamm, 2015-03-06 16:53:27]

The CQ bit was checked by slamm@chromium.org

[commit-bot: I haz the power, 2015-03-06 16:53:43]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/980073005/1

[commit-bot: I haz the power, 2015-03-06 23:00:52]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-06 23:01:45]

Patchset 1 (id:??) landed as
https://crrev.com/4a1bf1ab11f7e5a59a55aac9f45bc60b81e58b73
Cr-Commit-Position: refs/heads/master@{#319521}