Create services subdir under chrome/browser and add initial owners

The new services subdir contains all google services related codes,
currently including sync, invalidation and signin. We will move
those codes to this new unified directory in future patches.

BUG=314886
TEST=none
R=thakis@chromium.org, tim@chromium.org

Review URL: https://codereview.chromium.org/48123003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@233030 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/services/OWNERS

+tim@chromium.org
+zea@chromium.org