Added classes to enable session sync functionality.

TEST=ProfileSyncServiceSessionTest
BUG=30519

Original patch by jerrica@chromium.org
Original review: http://codereview.chromium.org/3168009

Review URL: http://codereview.chromium.org/3184004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@56423 0039d316-1c4b-4281-b951-d872f2087c98
46 files changed