Revert "Update all users of base::Version to explicitly specify the namespace, and clean up the header."

This is a speculative revert of r242414.

BUG=330681
TEST=as in bug
TBR=ben@chromium.org

Review URL: https://codereview.chromium.org/109673004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@242889 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 242889