Split history tests into parts that run in under 6 seconds.

I don't see how the failures listed in the bug can happen.  Because the logs are old, reenabling the tests to see if the failures re-occur.

BUG=26296
TEST=ExtensionHistoryApiTest.*

Review URL: http://codereview.chromium.org/6260050

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@73293 0039d316-1c4b-4281-b951-d872f2087c98
14 files changed