Merge "ImageDecoder: Use AssetFileDescriptor's length" am: efca2d56f1 am: 3a62413c4f am: b9d7c9ec52

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/1426968

Change-Id: I4c704fd27885b0b7b0d62e4e4d29f89d461d879d