Rename Size_ to Size

Previouslty "Size" was reserved by protoc-gen-gogoctrd and user-generated
"Size" was automatically renamed to "Size_" to avoid conflicts.

Signed-off-by: Kazuyoshi Kato <katokazu@amazon.com>

snapshots/proxy/proxy.go

@@ -216,7 +216,7 @@ func toInfo(info *snapshotsapi.Info) snapshots.Info {
 func toUsage(resp *snapshotsapi.UsageResponse) snapshots.Usage {
 	return snapshots.Usage{
 		Inodes: resp.Inodes,
-		Size:   resp.Size_,
+		Size:   resp.Size,
 	}
 }