Move service_manager to top level dir

BUG=None
TEST=Existing
TBR=darin

Review URL: https://codereview.chromium.org/180243020

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@253973 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 253973