Move the mStrictModeCallbacks to be self-locked

We can't use AMS lock here since it's potentially called from
many places with other locks held.

Bug: 339293659
Bug: 378505461
Test: treehugger
Flag: EXEMPT bugfix
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:3e79e0fb88b8b86bea2d919a2b937781922927b4)
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:65fee27021a089695bbb623d1d561e20f416a649)
Merged-In: I552e3e1c680fde2f707c6dda7fd26940bd9974ce
Change-Id: I552e3e1c680fde2f707c6dda7fd26940bd9974ce