Add missing gRPC include.

Othewise the header is not self contained and breaks when
upgrading gRPC.

Bug: 279548314
Test: presubmit
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:3d3baed1bc85f8ddddb2764a5a09cd4d578419f0)
Merged-In: Ife50863bd16eda6bc639261b1f91fdfcf48f6294
Change-Id: Ife50863bd16eda6bc639261b1f91fdfcf48f6294
diff --git a/automotive/vehicle/aidl/impl/grpc/GRPCVehicleHardware.h b/automotive/vehicle/aidl/impl/grpc/GRPCVehicleHardware.h
index 90588aa..e740da7 100644
--- a/automotive/vehicle/aidl/impl/grpc/GRPCVehicleHardware.h
+++ b/automotive/vehicle/aidl/impl/grpc/GRPCVehicleHardware.h
@@ -24,6 +24,8 @@
 #include "VehicleServer.grpc.pb.h"
 #include "VehicleServer.pb.h"
 
+#include <grpc++/grpc++.h>
+
 #include <atomic>
 #include <chrono>
 #include <condition_variable>