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

Change-Id: Ifa59a2f2136dd0704097411ee183925e6c387fae
2 files changed