Use more precise names for protobuf and nano

io.grpc.nano sort of seems like a "small" version of grpc-java. And
io.grpc.proto could also mean multiple things. Using "protobuf"
and "protobuf nano" gets us consistent names that are still
understandable, predictable, and more similar to protobuf project
itself.
diff --git a/compiler/src/test/golden/TestService.java.txt b/compiler/src/test/golden/TestService.java.txt
index a19f90c..081ef00 100644
--- a/compiler/src/test/golden/TestService.java.txt
+++ b/compiler/src/test/golden/TestService.java.txt
@@ -19,32 +19,32 @@
       io.grpc.testing.integration.Test.SimpleResponse> METHOD_UNARY_CALL =
       io.grpc.stub.Method.create(
           io.grpc.MethodType.UNARY, "UnaryCall",
-          io.grpc.proto.ProtoUtils.marshaller(io.grpc.testing.integration.Test.SimpleRequest.PARSER),
-          io.grpc.proto.ProtoUtils.marshaller(io.grpc.testing.integration.Test.SimpleResponse.PARSER));
+          io.grpc.protobuf.ProtoUtils.marshaller(io.grpc.testing.integration.Test.SimpleRequest.PARSER),
+          io.grpc.protobuf.ProtoUtils.marshaller(io.grpc.testing.integration.Test.SimpleResponse.PARSER));
   private static final io.grpc.stub.Method<io.grpc.testing.integration.Test.StreamingOutputCallRequest,
       io.grpc.testing.integration.Test.StreamingOutputCallResponse> METHOD_STREAMING_OUTPUT_CALL =
       io.grpc.stub.Method.create(
           io.grpc.MethodType.SERVER_STREAMING, "StreamingOutputCall",
-          io.grpc.proto.ProtoUtils.marshaller(io.grpc.testing.integration.Test.StreamingOutputCallRequest.PARSER),
-          io.grpc.proto.ProtoUtils.marshaller(io.grpc.testing.integration.Test.StreamingOutputCallResponse.PARSER));
+          io.grpc.protobuf.ProtoUtils.marshaller(io.grpc.testing.integration.Test.StreamingOutputCallRequest.PARSER),
+          io.grpc.protobuf.ProtoUtils.marshaller(io.grpc.testing.integration.Test.StreamingOutputCallResponse.PARSER));
   private static final io.grpc.stub.Method<io.grpc.testing.integration.Test.StreamingInputCallRequest,
       io.grpc.testing.integration.Test.StreamingInputCallResponse> METHOD_STREAMING_INPUT_CALL =
       io.grpc.stub.Method.create(
           io.grpc.MethodType.CLIENT_STREAMING, "StreamingInputCall",
-          io.grpc.proto.ProtoUtils.marshaller(io.grpc.testing.integration.Test.StreamingInputCallRequest.PARSER),
-          io.grpc.proto.ProtoUtils.marshaller(io.grpc.testing.integration.Test.StreamingInputCallResponse.PARSER));
+          io.grpc.protobuf.ProtoUtils.marshaller(io.grpc.testing.integration.Test.StreamingInputCallRequest.PARSER),
+          io.grpc.protobuf.ProtoUtils.marshaller(io.grpc.testing.integration.Test.StreamingInputCallResponse.PARSER));
   private static final io.grpc.stub.Method<io.grpc.testing.integration.Test.StreamingOutputCallRequest,
       io.grpc.testing.integration.Test.StreamingOutputCallResponse> METHOD_FULL_DUPLEX_CALL =
       io.grpc.stub.Method.create(
           io.grpc.MethodType.DUPLEX_STREAMING, "FullDuplexCall",
-          io.grpc.proto.ProtoUtils.marshaller(io.grpc.testing.integration.Test.StreamingOutputCallRequest.PARSER),
-          io.grpc.proto.ProtoUtils.marshaller(io.grpc.testing.integration.Test.StreamingOutputCallResponse.PARSER));
+          io.grpc.protobuf.ProtoUtils.marshaller(io.grpc.testing.integration.Test.StreamingOutputCallRequest.PARSER),
+          io.grpc.protobuf.ProtoUtils.marshaller(io.grpc.testing.integration.Test.StreamingOutputCallResponse.PARSER));
   private static final io.grpc.stub.Method<io.grpc.testing.integration.Test.StreamingOutputCallRequest,
       io.grpc.testing.integration.Test.StreamingOutputCallResponse> METHOD_HALF_DUPLEX_CALL =
       io.grpc.stub.Method.create(
           io.grpc.MethodType.DUPLEX_STREAMING, "HalfDuplexCall",
-          io.grpc.proto.ProtoUtils.marshaller(io.grpc.testing.integration.Test.StreamingOutputCallRequest.PARSER),
-          io.grpc.proto.ProtoUtils.marshaller(io.grpc.testing.integration.Test.StreamingOutputCallResponse.PARSER));
+          io.grpc.protobuf.ProtoUtils.marshaller(io.grpc.testing.integration.Test.StreamingOutputCallRequest.PARSER),
+          io.grpc.protobuf.ProtoUtils.marshaller(io.grpc.testing.integration.Test.StreamingOutputCallResponse.PARSER));
 
   public static TestServiceStub newStub(io.grpc.Channel channel) {
     return new TestServiceStub(channel, CONFIG);