Stop storing the direction buffer

We pull the information out of the direction buffer_type immediately and pack
it safely in to privates where it can be accessed with sane accessors.

Test: unit tests
Bug: 24410295
Change-Id: I84e4cf50aad9202210fc9c3db5dd78858991ecd7
Signed-off-by: Casey Dahlin <sadmac@google.com>
7 files changed