Separate the binder backend from android_engine

Create a pure virtual class "KeystoreBackend" which supplies the
crypto methods used by android_engine.  Create a KestoreBackendBinder
class which implements the binder backend as a no-op change that
will allow future backends to be added.

Bug: 34603782
Test: Compiles
Change-Id: I16620aba569bd53290145b2b30242c4888106d0a
5 files changed
tree: 36248023c593e9a1a15e9cf2c049ca1949d1d065
  1. keystore/
  2. keystore-engine/
  3. softkeymaster/
  4. MODULE_LICENSE_APACHE2
  5. NOTICE