Display total storage for Internal shared storage.
Prior to this change, Settings was using
volume.getPath().getTotalBytes() to calculate the total, which includes
the user-accessible storage, but not the internal partitions. As such,
the total displayed was often missing many GBs (for example, in a 32GB
device, it could display "12.09GB of 25.01GB used".
This change fix this problem by using the total size and creating a
"System" section containing the "missing" storage.
BUG:
24128505
Change-Id: Ic35cd7c8406eff16ac1d97c4b4c233ecde64a6e1