RefCounted types should not have public destructors - sync and jingle

In the process of ensuring no base classes for RefCounted classes have
public destructors, base::NonThreadSafe shows up frequently due to having
a public destructor.

Begin migrating all the code that has a base::NonThreadSafe member to
directly inheriting from base::NonThreadSafe, so that base::NonThreadSafe's
destructor can be made private.

BUG=123295
TEST=existing


Review URL: https://chromiumcodereview.appspot.com/10411046

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@141530 0039d316-1c4b-4281-b951-d872f2087c98
28 files changed