Change FreeMemory and TotalMemory behavior.

TotalMemory is now equal to the footprint limit (around when the
next GC will occur).
FreeMemory is now equal to TotalMemory() - bytes_allocated_.
Also added more memory dumping info to DumpGcPerformanceInfo.

Bug: 16520008
Bug: 15819878

(cherry picked from commit dd162fb5990cedf80a5093ecc0e77df82af5f754)

Change-Id: I68239a5295cc1372b3995eb781d67b9e25d6eaed
2 files changed