Merge pull request #7469 from yang-g/proto_lite

Add a macro to support protobuf lite

include/grpc++/impl/codegen/config_protobuf.h

@@ -40,9 +40,14 @@
 #endif
 
 #ifndef GRPC_CUSTOM_MESSAGE
+#ifdef GRPC_USE_PROTO_LITE
+#include <google/protobuf/message_lite.h>
+#define GRPC_CUSTOM_MESSAGE ::google::protobuf::MessageLite
+#else
 #include <google/protobuf/message.h>
 #define GRPC_CUSTOM_MESSAGE ::google::protobuf::Message
 #endif
+#endif
 
 #ifndef GRPC_CUSTOM_DESCRIPTOR
 #include <google/protobuf/descriptor.h>