Add real to elapsed offset to shell transition trace am: 541c4b60 am: 3c467056 am: 9fb472fb

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



Change-Id: Ifff8fb248d95ed2b17cca861dde57137a749b56d
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>