Split out jank data from policy

Move ProfileData out to its own file with helper
accessors. This keeps policy (what is/isn't jank)
outside of the data storage.

Also use lambdas to iterate over the histogram
to make it nicer for dumping & proto-ifying.

Test: hwui_unit_tests pass & jank data still dumps

Change-Id: I88488369ec77590a2867f51128e65bb786aa34e6