Respect cookies set in a 401 responses when restarting the http transaction.

There are two parts to this change:
(1) rebuild the request cookies before each transaction restart for
    authentication
(2) notify the URLRequestHttpJob of header completion before *each*
    transaction restart for authentication

By "each transaction" I mean the automatic restarts that don't require
user input, such as:
 - replying to the first step of NTLM
 - selecting identity embedded in URL
 - selecting identity in auth-cache

Needing to notify URLRequestHttpJob for these intermediate restarts is
a consequence of cookie store management being done outside of
HttpNetworkTransaction.

After updating the cookie store, URLRequestHttpJob now tests
|HttpTransaction::IsReadyToRestartForAuth()| to check whether the
notification was informational or an identity is actually needed.

R=wtc
BUG=6450
Review URL: http://codereview.chromium.org/51004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@12635 0039d316-1c4b-4281-b951-d872f2087c98
15 files changed