Fix trampoline activities when relaunching PiP

- We should be checking the actual launched-from package since that stores
  the source package across trampoline activities

Bug: 35458117
Test: Enter PiP from a trampoline activity, launch again from Launcher
      and ensure that it is expanded

Change-Id: Ia0e586e8b21dee63b513bd61a41a24e7da4325e1