Refactor AndroidKeymaster so all methods use message objects.

Methods with simple argument or return types eschewed message objects,
but this complicates the TrustyKeymaster implementation by requiring it
to build its own system for marshalling and unmarshalling.

Bug: 14674558
Change-Id: I5a88523c9d1a76c8629ff6f93040ceb3c2a9426b
7 files changed