Mojo JS bindings: flip the default value of use_new_js_bindings to true.

chrome/browser/engagement/BUILD.gn

Index: chrome/browser/engagement/BUILD.gn
diff --git a/chrome/browser/engagement/BUILD.gn b/chrome/browser/engagement/BUILD.gn
index 3bca05363d53123f5c552a820cc85768a08f2fb9..2f45dd439d7ebd330b7e87f3ddcafce27f3934ed 100644
--- a/chrome/browser/engagement/BUILD.gn
+++ b/chrome/browser/engagement/BUILD.gn
@@ -15,4 +15,7 @@ mojom("mojo_bindings") {
 
   # TODO(crbug.com/714018): Convert the implementation to use OnceCallback.
   use_once_callback = false
+
+  # TODO(crbug.com/699569): Convert to use the new JS bindings.
+  use_new_js_bindings = false
 }