Revert 449036, which rolled back 402098, and fix the valgrind error that caused the original rollback:

      Revert 33394 (due to valgrind errors) - Appcache update support for pending
master entries:
 Update process issues a URL request to fetch pending master entries.
 Pending master entry fetch logic kept separate from regular url fetching as
this will be the case in the longterm solution.
 No optimizations to avoid issuing URL request if pending master entry is also
listed in the manifest. (simpler)
 Only optimized to prevent refetching something that has already been
successfully fetched.

Longterm optimized solution should be to siphon the responses as the master
resource is downloaded instead of having the update job issue URL requests.


TEST=new tests for update jobs with pending master entries
BUG=none

Review URL: http://codereview.chromium.org/449039

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@33410 0039d316-1c4b-4281-b951-d872f2087c98