Add real to elapsed offset to shell transition trace am: 541c4b60 am: 3c467056

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/22988307



Change-Id: I11ae8290e9425dc23e154f19fbc9c802c474cad3
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>