Change the default number of proxy resolver threads used for evaluating PAC scripts from 1 to 4.

Also adds a command line flag to override the default: --num-pac-threads=X

BUG=11079
Review URL: http://codereview.chromium.org/2893005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@52046 0039d316-1c4b-4281-b951-d872f2087c98
8 files changed