tree c4044f48e01a0821fe95d0768f531f96abccdbeb
parent 7a1f1d8a8579278048c044b7aca5d0d58ece57e4
author Jorim Jaggi <jjaggi@google.com> 1484569019 +0100
committer Jorim Jaggi <jjaggi@google.com> 1484842002 +0100

Persist task snapshots to disk

So they can be used again after rebooting or when the process gets
killed, but the snapshot is still used for recents.

Also implement TaskSnapshotLoader, to restore it from disk. The
infrastructure around restoring and caching snapshots for recents
will be implemented in the next CL.

Test: runtest frameworks-services -c
com.android.server.wm.TaskSnapshotPersisterLoaderTest

Bug: 31339431
Change-Id: Iaec03c4cc92e04b6dd7e623bca755ddc92613bce