GenericSource: reset mDrmManagerClient when mDataSource is cleared. am: 224858e719 am: 69c8e36da7 am: 3fcddfd23a am: e01ba47052 am: adadada4f0 am: ddb3d77dad am: 301a55c115
am: 8a7f184caf

* commit '8a7f184cafecef52322e7a3999096fa20cd1a93a':
  GenericSource: reset mDrmManagerClient when mDataSource is cleared.