media: Use native CDM enum types in media mojo interfaces

media/mojo/services/mojo_cdm_promise.cc

Index: media/mojo/services/mojo_cdm_promise.cc
diff --git a/media/mojo/services/mojo_cdm_promise.cc b/media/mojo/services/mojo_cdm_promise.cc
index 430360b326179a2196a23baa8a305eb872a10c83..2de75b91b01c4a34a66e44c43052e603e1eab6d0 100644
--- a/media/mojo/services/mojo_cdm_promise.cc
+++ b/media/mojo/services/mojo_cdm_promise.cc
@@ -21,7 +21,7 @@ static mojom::CdmPromiseResultPtr GetRejectResult(
     const std::string& error_message) {
   mojom::CdmPromiseResultPtr cdm_promise_result(mojom::CdmPromiseResult::New());
   cdm_promise_result->success = false;
-  cdm_promise_result->exception = static_cast<mojom::CdmException>(exception);
+  cdm_promise_result->exception = exception;
   cdm_promise_result->system_code = system_code;
   cdm_promise_result->error_message = error_message;
   return cdm_promise_result;