Part of #1971384: [META] Convert page callbacks to controllers
For instructions on how to convert a page callback into a controller, see the WSCCI Conversion Guide.
Need to rewrite the whole module to make test sync with current test implementation. For more details, please refer: #1988802: [META] Rewrite test modules in system to provide better unit testing.
Now a duplicate of #2066557: Convert system.module's test's database_test.module's JSON functions to a new-style controller..
Drupal is a registered trademark of Dries Buytaert.