Add a command line flag to change the default number of parallel DNS requests issued by chrome.

  --host-resolver-parallelism=XXX

This is a useful debugging tool, since for some users too many parallel DNS requests results in spurious DNS failures from their resolver.

BUG=44489
Review URL: http://codereview.chromium.org/3019007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@52802 0039d316-1c4b-4281-b951-d872f2087c98
16 files changed