Rename LargeBitmap to BitmapRegionDecoder for having a better API.

Move AssetStreamAdaptor, AutoFDSeek and nullObjectReturn to Utils.h because
BitmapFactory.cpp and BitmapRegionDecoder.cpp both need to use these utility functions.

Change-Id: I3e60c7fe4abd0289e1384e69a08fd20fe6fb0e10
10 files changed