Allow for more than one home app.

Having a single mHomeProcess in ActivityManagerService ignores the
possibility of multiple processes serving as home. Particularly when
we have a home activity that only serves to launch the true home
activity.

Fixes bug b10296766

Change-Id: I9e5c9c955c64f4b3df856b6bc66d6a0d93f85aab
3 files changed