Currently warns if you exceed more than 25% and 2*100%*timeUsed/(timeUsed+totalTime)
The formula means that imagining you've got half of the remaining time that you really have,
we will warn you if you would exceed the quota given your rate so far. It's generous during the
early to mid-life and converges back to the limit as your timeUsed approaches totalTime.
bug:2576057
Change-Id: Id189de5b026f927ef478fd212d61d9e4ab5239e6
e2c0ce0363