Check for updates for a user script only if it has an update URL.

chrome/browser/sync/glue/extension_util.cc

Index: chrome/browser/sync/glue/extension_util.cc
diff --git a/chrome/browser/sync/glue/extension_util.cc b/chrome/browser/sync/glue/extension_util.cc
index 1fad37e1d3be6fccf8517a39976dd1518bd0f9d8..f1cd20fe7c050b0576cd42afaeb2d97505dab9c9 100644
--- a/chrome/browser/sync/glue/extension_util.cc
+++ b/chrome/browser/sync/glue/extension_util.cc
@@ -28,6 +28,12 @@ bool IsExtensionSyncable(const Extension& extension) {
     return false;
   }
 
+  // Reject converted user scripts that don't have an auto-update URL.
+  if (extension.converted_from_user_script() &&
+      extension.update_url().is_empty()) {
+    return false;
+  }
+
   // TODO(akalin): Figure out if we need to allow some other types.
   if (extension.location() != Extension::INTERNAL) {
     // We have a non-standard location.