GenericSource: reset mDrmManagerClient when mDataSource is cleared. am: 224858e719 am: 69c8e36da7 am: 3fcddfd23a am: e01ba47052 am: adadada4f0
am: ddb3d77dad

* commit 'ddb3d77dad1766708fdb18cc48e60a663ee8e2e1':
  GenericSource: reset mDrmManagerClient when mDataSource is cleared.