Log the right workspace id for -1 screen for stop and resume.

Test: manual
Bug: 137952354

Logs after this fix:
08-01 12:01:36.220 17105 17105 D UserEvent: action:STOP
08-01 12:01:36.220 17105 17105 D UserEvent:  Source child:WORKSPACE id=-1
08-01 12:01:36.220 17105 17105 D UserEvent:  Elapsed container 5511 ms, session 5511 ms, action 0 ms
08-01 12:01:36.220 17105 17105 D UserEvent:
08-01 12:01:38.042 17105 17105 D UserEvent:
08-01 12:01:38.042 17105 17105 D UserEvent: -----------------------------------------------------
08-01 12:01:38.042 17105 17105 D UserEvent: action:RESUME
08-01 12:01:38.042 17105 17105 D UserEvent:  Source child:WORKSPACE id=-1
08-01 12:01:38.042 17105 17105 D UserEvent:  Elapsed container 7334 ms, session 7334 ms, action 0 ms
08-01 12:01:38.042 17105 17105 D UserEvent:

Change-Id: Ic2d88eee3ff7a0e28d5c7e4cab8ee61952ed95ee