Don't get extras from the Intent

When handling Intents in the system process, we need to be careful
to not cause the extras bundle to be unparcelled. If the extra is
unparcelled, any custom class added to the extras will throw a
ClassCastException during the unparcel. For legacy reasons, we
would get the "seq" extra from the Intent for broadcast debugging.
This violates our requirement to not unparcel extras in the system
server process.

Bug: 19068243
Change-Id: I6cac426a0ef8648a05ded69ee4ac244017d9b5d1