- Now we always use a fragment as a callback, rather than assuming the parent
activity implements it.
- Use a generics trick to make sure the callback fragments really implements
Callback.
(Might be abuse of a language feature, but it's at least safer than runtime
check...)
Bug 4314669
Bug 4345496
Change-Id: If4048d456b298784097e202cffab170177ac7b2d
4e033e0ac7