Adding a .nano prefix in the proto package name

Change-Id: Ia513089f813567953ca146538f79d21ca5fd8ddf
diff --git a/protos/backup.proto b/protos/backup.proto
index 6704e08..c3f27e1 100644
--- a/protos/backup.proto
+++ b/protos/backup.proto
@@ -18,7 +18,7 @@
 
 package launcher_backup;
 
-option java_package = "com.android.launcher3.backup";
+option java_package = "com.android.launcher3.backup.nano";
 option java_outer_classname = "BackupProtos";
 
 message Key {