DO NOT MERGE ANYWHERE:Fix NPE during Activity transition using wrong Activity.
Bug 30786309
If the Activity used in makeSceneTransitionAnimation isn't
the same one used in the startActivity call, a NullPointerException
could be thrown.
Change-Id: Id21c54fcf99b353feab62f7fc160997ed06e7d23
(cherry picked from commit 3289bfa2)
(cherry picked from commit a3edbf6a)