Revert 289433 &quotRefactor pooling logic into a helper method&quot

      Reason for revert:
Causes crashes in canary.

> Refactor pooling logic into a helper method
> Disable pooling when there are cert errors.
> Disable pooling when pinning does not match for the new host.
> 
> BUG=398925
> 
> Review URL: https://codereview.chromium.org/425803014

TBR=rch@chromium.org

Review URL: https://codereview.chromium.org/476113003

Cr-Commit-Position: refs/heads/master@{#289937}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@289937 0039d316-1c4b-4281-b951-d872f2087c98