Serve mojo WebUI resources from the same origin as the WebUI itself.

chrome/browser/ui/webui/engagement/site_engagement_ui.cc

Index: chrome/browser/ui/webui/engagement/site_engagement_ui.cc
diff --git a/chrome/browser/ui/webui/engagement/site_engagement_ui.cc b/chrome/browser/ui/webui/engagement/site_engagement_ui.cc
index 0ae81f98dea8cac48957b4173b6f3023bb275d40..f756bc59f93b81b61869cb2ac38a92a1fea84b89 100644
--- a/chrome/browser/ui/webui/engagement/site_engagement_ui.cc
+++ b/chrome/browser/ui/webui/engagement/site_engagement_ui.cc
@@ -70,13 +70,13 @@ SiteEngagementUI::SiteEngagementUI(content::WebUI* web_ui)
   source->AddResourcePath("engagement_table.js",
                           IDR_SITE_ENGAGEMENT_ENGAGEMENT_TABLE_JS);
   source->AddResourcePath("site_engagement.js", IDR_SITE_ENGAGEMENT_JS);
+  source->AddResourcePath(
+      "chrome/browser/ui/webui/engagement/site_engagement.mojom",
+      IDR_SITE_ENGAGEMENT_MOJO_JS);
+  source->AddMojoResources();
   source->SetDefaultResource(IDR_SITE_ENGAGEMENT_HTML);
 
   content::WebUIDataSource::Add(Profile::FromWebUI(web_ui), source.release());
-
-  AddMojoResourcePath(
-      "chrome/browser/ui/webui/engagement/site_engagement.mojom",
-      IDR_SITE_ENGAGEMENT_MOJO_JS);
 }
 
 SiteEngagementUI::~SiteEngagementUI() {}