Prevent activity token leaked to another process

Malicious app could register the organizer via one-way binder call
to disguise as running on pid 0.

Bug: 367266072
Bug: 446678690
Test: verified via the sample app
Flag: EXEMPT bugfix
Cherrypick-From: https://googleplex-android-review.googlesource.com/q/commit:61ab2b65caf855c48fdb4166f94e02bf79c90e7b
Cherrypick-From: https://googleplex-android-review.googlesource.com/q/commit:787be3fc17ac4d7970ef8eed7c2906653ec67df2
Cherrypick-From: https://googleplex-android-review.googlesource.com/q/commit:5b63716bff30adbf12a4236e8acdb70fb1a4fa72
Merged-In: I51378c7d2da06fb83670abd082a089cfd82d699d
Change-Id: I51378c7d2da06fb83670abd082a089cfd82d699d