frameworks/base: add app launch timeline instrumentation

Displayed Activity is often being used to measure application
launch times. However Displayed Activity only accounts for a
subset of the app launch. This additional instrumentation will
allow for more accurate measurements of applications launch
times.

Change-Id: Ic0bc6f0110c3ecbbce9eccd9357818a8a898475e
framework/base: get proper obb mountpoint based on user handle

Due to invalid obb mount point, CTS test case was failing to mount
obb file at /mnt/shell/emulated/0. Added new API to support user
based mount point for obb.

Change-Id: I9f113bd98ab3a4af00dd7f788b2dc3bc45627d6c
CRs-Fixed: 587497