[GCM] Make GCMProfileService persist check-in info

R=fgorski@chromium.org, zea@chromium.org
TBR=zea@chromium.org
BUG=284553
TEST=new tests added

Review URL: https://codereview.chromium.org/79433008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@237394 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 237394