Allows the user to limit the stream to a subset of the entire file.
SkFILEStream uses the current FILE position as the base position for the
stream; this allows the user to further limit the length of the stream
to a range of bytes in the file.
Change-Id: I36131ff19e75b65d501eabdfd9368f8fbb2e177f
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/316357
Commit-Queue: Ben Wagner <bungeman@google.com>
Reviewed-by: Leon Scroggins <scroggo@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
e4383b8f1e