PP_OPTIONAL       618 ppapi/tests/test_case.h     set_callback_type(PP_OPTIONAL); \
PP_OPTIONAL       672 ppapi/tests/test_case.h     set_callback_type(PP_OPTIONAL); \
PP_OPTIONAL       242 ppapi/tests/test_graphics_2d.cc   TestCompletionCallback cb(instance_->pp_instance(), PP_OPTIONAL);
PP_OPTIONAL       281 ppapi/tests/test_utils.cc       callback_type_(PP_OPTIONAL),
PP_OPTIONAL       292 ppapi/tests/test_utils.cc       callback_type_(force_async ? PP_REQUIRED : PP_OPTIONAL),
PP_OPTIONAL       364 ppapi/tests/test_utils.cc   else if (callback_type_ == PP_OPTIONAL)
PP_OPTIONAL       252 ppapi/tests/test_utils.h   if (callback_.callback_type() == PP_OPTIONAL)