Update DataTables only after previous call is done

When the update is always made at a set interval, the next update could
be called before the previous one has completed. Data inconsistencies
could arise from changes being made out of order in the updates. Move
the code to call the next update to the "complete" function to make sure
the previous call has finished before starting the next one.

Change-Id: I946912a30934e8d25f83fadaef7c2b8b6db269b2
Closes-Bug: #1231751
Avoid discarding precision of metering data

Fixes bug 1241467

Narrow-casting statistical aggregates to int before inserting
into the resource usage line charts had the effect of unnaturally
smoothening the trend. This was especially apparent for meters
defined over a narrow range (such as cpu_util ranging from 0.0%
to 100.0%).

We now maintain floating point precision for these data.

Change-Id: If6141a4f66aa0078d38aa9f53d913aca5684ad94
Merge "Avoid discarding precision of metering data"
Merge "Update DataTables only after previous call is done"