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

content/browser/webui/web_ui_data_source_impl.h

Index: content/browser/webui/web_ui_data_source_impl.h
diff --git a/content/browser/webui/web_ui_data_source_impl.h b/content/browser/webui/web_ui_data_source_impl.h
index d9f44887d1ce7b030359e073a16b737f63132b14..48db032d077786aef6ab4338a00f0151e945699e 100644
--- a/content/browser/webui/web_ui_data_source_impl.h
+++ b/content/browser/webui/web_ui_data_source_impl.h
@@ -38,6 +38,7 @@ class CONTENT_EXPORT WebUIDataSourceImpl
   void SetDefaultResource(int resource_id) override;
   void SetRequestFilter(
       const WebUIDataSource::HandleRequestCallback& callback) override;
+  void AddMojoResources() override;
   void DisableReplaceExistingSource() override;
   void DisableContentSecurityPolicy() override;
   void OverrideContentSecurityPolicyObjectSrc(const std::string& data) override;