Refactor fstrim code to be encapsulated in unique task object, and
give it option of benchmarking when finished. Trimming now includes
both storage from fstab and adopted private volumes. Cleaner timing
stats are logged for each unique volume.
Add wakelock during ongoing async move tasks. Push disk sysfs path
to framework so it can parse any SD card registers as desired.
Bug: 21831325
Change-Id: I76577685f5cae4929c251ad314ffdaeb5eb1c8bf
