content/test: Move LocalHostResolverProc into BrowserTestBase from ChromeTestSuite.

Moving LocalHostResolverProc into content makes it usable for content_browsertests and
interactive_ui_tests (in addition to browser_tests).

BUG=none
R=jam@chromium.org

Review URL: https://codereview.chromium.org/23736011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@224866 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 224866