base

Fix recents list for multiuser

Since the Recents is now an activity running in the respective user's sandbox,
it shouldn't use the special API to get the current user's recent tasks.
Otherwise it causes all users to fetch the state of the current foreground user
instead of their own recents.

Change-Id: Ice8c2978e6a7ae71c44666c79a19ac07a2cbea1b