Switched Telemetry BrowserBackend to use 127.0.0.1 instead of localhost.

This speeds up requests on Windows significantly.

BUG=305367
R=dtu@chromium.org, kbr@chromium.org

Review URL: https://codereview.chromium.org/26595002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@227639 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 227639