RefCounted types should not have public destructors, delegate cleanup

For Delegate/Observer-type classes that specify an
interface but do not have any particular lifetime
requirements, make their destructors protected. This is to
allow their interfaces to be implemented safely by
RefCounted types. With public destructors, it's possible to
do "scoped_ptr<Delegate> foo", and then assign a
RefCountedDelegateImpl, which would lead to a double free.

As none of these Delegates actually need public destructors
(ownership of the Delegate* is not transferred during a
function call / class constructor), mark the destructors
protected so that it becomes a compile warning to try to
delete them via the Delegate*.

BUG=123295
TEST=it compiles


Review URL: https://chromiumcodereview.appspot.com/10383262

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@144086 0039d316-1c4b-4281-b951-d872f2087c98
56 files changed