Give mojo_shell a TransportSecurityPersister.

This required moving TransportSecurityPersister into net.

BUG=310293
R=akalin@chromium.org, thestig@chromium.org

Review URL: https://codereview.chromium.org/59693008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@234667 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 234667