gRPC migration

Change-Id: I3129ae27d7ee12a23c7046f0d877e8064f2fd7f4
diff --git a/vendor/google.golang.org/protobuf/internal/impl/encode.go b/vendor/google.golang.org/protobuf/internal/impl/encode.go
index 8c8a794..845c67d 100644
--- a/vendor/google.golang.org/protobuf/internal/impl/encode.go
+++ b/vendor/google.golang.org/protobuf/internal/impl/encode.go
@@ -79,8 +79,9 @@
 		size += f.funcs.size(fptr, f, opts)
 	}
 	if mi.unknownOffset.IsValid() {
-		u := *p.Apply(mi.unknownOffset).Bytes()
-		size += len(u)
+		if u := mi.getUnknownBytes(p); u != nil {
+			size += len(*u)
+		}
 	}
 	if mi.sizecacheOffset.IsValid() {
 		if size > math.MaxInt32 {
@@ -141,8 +142,9 @@
 		}
 	}
 	if mi.unknownOffset.IsValid() && !mi.isMessageSet {
-		u := *p.Apply(mi.unknownOffset).Bytes()
-		b = append(b, u...)
+		if u := mi.getUnknownBytes(p); u != nil {
+			b = append(b, (*u)...)
+		}
 	}
 	return b, nil
 }