Sub-task of #1889790: [Meta] Allow modules to register links for menus, breadcrumbs and tabs (if not with hook_menu)
Problem/Motivation
Breadcrumbs use a static pattern but should be updated to a service to get the functions out of the global scope.
Breadcrumbs are a sticking point in the panel-ish controller conversion.
Proposed resolution
Create a service to manage breadcrumbs
Create a block for breadcrumbs that has the service injected.
Place this block in the appropriate region in standard install profile.
Remaining tasks
Create the class and register the service
Write the block plugin
Write the standard.install integration
User interface changes
Breadcrumbs becomes a block
API changes
drupal_get_breadcrumb and drupal_set_breadcrumb
would become
<?php
Drupal::service('breadcrumb')->get()
?><?php
Drupal::service('breadcrumb')->set()
?>Add
<?php
Drupal::service('breadcrumb')->append()
?><?php
Drupal::service('breadcrumb')->insert()
?>