The application adds a new custom permission called VIEW_DOCKBAR inside the "General Permissions" section of the role configuration (except for Guest role).
With this new custom permission, frontend developers can leverage the Liferay permission system to show/hide the portal dockbar inside a custom theme.

Here's how to initialize a Freemarker variable inside the init_custom.ftl file of a custom theme:
<#assign viewDockbar = permissionChecker.hasPermission(themeDisplay.scopeGroupId, "90", "90", "VIEW_DOCKBAR") />

And here's how to use the Freemarker variable:
<#if viewDockbar>
<@liferay.control_menu />
</#if>

On Liferay 7.4+ you need to add this property to your portal-ext.properties file in order to make it working:
resource.actions.strict.mode.enabled=false