Add parsing of in-memory strings

Some times, specifically in unit tests, we might want to parse a string
instead of an actual file. And now we can!

Change-Id: Iafdb0f0c1c4002c281de8e819da07a32b10694bf
Test: unit tests
Bug: 24385461
Signed-off-by: Casey Dahlin <sadmac@google.com>
2 files changed