Move coverage bitmap from FontCollection to FontFamily

This will significantly reduce memory usage and also speed the creation
of new font families. In particular, the coverage bitmaps for the fonts
in the fallback stack will be computed once in the Zygote, rather than
separately in each app process.

Bug: 17756900
Change-Id: I66f5706bddd4658d78fe5b709f7251ca9d2ff4f8
4 files changed
tree: 1de01efab8dc3c9ec5026fa93cfe3d60d0d5d217
  1. include/
  2. libs/
  3. sample/