hook_views_api() removed and foo.views.inc has to be placed in the module directory

In order to simplify the way to integrate a module with views , hook_views_api() has been removed. This means that you can no longer place the .views.inc file in a subdirectory. It now must be in a .views.inc file in the root of your module.

Drupal 7

foo/foo.module

function example_views_api() {
  return array(
    'api' => 3.0,
  );
}

foo/views/foo.views.inc

function foo_views_data() {
  ...
}

Drupal 8

foo/foo.views.inc

function foo_views_data() {
  ...
}