Mojo: Remove utility:: namespace

Public facing APIs should just live in the mojo:: namespace.

R=sky@chromium.org, viettrungluu@chromium.org

Review URL: https://codereview.chromium.org/128803002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@243799 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 243799