Update the smearing methods in framework.

1. Fix the bug about foregroundActivityTime. It should take microseconds
as parameter and return microseconds
2. Use the min time of foregroundActivity time and Top time as "screen
time"
3. Hide bluetooth, wifi, idle but don't smear it

Bug: 63176214
Test: runtest -x BatteryStatsHelperTest
Change-Id: I5798577da17d60fb3e3b18351deb31ae77939154