Kill floating activities running in the same thread when tapping outside
This change makes all activities from the same app to be finished when we tap outside the halo window. Other apps running in different threads
(floating or not) won't be finished.

Port from here: ParanoidAndroid/android_frameworks_base@f489f45

Change-Id: I9a6080d8e509089197c27ba415bf1f93bf74cd30