Merge changes I5b94a8f0,Ie6cdd846,Ie6b5f5e6,Ib962edf6,I9d779b2d, ...

* changes:
  Add an extra debug flag to BackgroundDexOptimizer
  Some refactoring in BackgroundDexOptService.
  Do not try to resolve realpath in DexManager.
  Log DexManager realpath errors only in debug mode.
  Record data about dex files use on disk
  Add logic for recording dex files use on disk