Change record status: 
Project: 
Introduced in branch: 
8.x
Introduced in version: 
8.0-alpha3
Description: 

BreadcrumbBuilderBase is added to remove the boilerplate code from BreadcrumbBuilders

Before

<?php
use Drupal\Core\Access\AccessManager;
use
Drupal\Core\Breadcrumb\BreadcrumbBuilderInterface;
use
Drupal\Core\Entity\EntityManagerInterface;
use
Drupal\node\NodeInterface;
/**
* Provides a breadcrumb builder for nodes in a book.
*/
class BookBreadcrumbBuilder implements BreadcrumbBuilderInterface{
?>

After

<?php
use Drupal\Core\Access\AccessManager;
use
Drupal\Core\Breadcrumb\BreadcrumbBuilderBase;
use
Drupal\Core\Entity\EntityManagerInterface;
use
Drupal\node\NodeInterface;
/**
* Provides a breadcrumb builder for nodes in a book.
*/
class BookBreadcrumbBuilder extends BreadcrumbBuilderBase {
?>

BreadcrumbBuilderBase also provides BreadcrumbBuilderBase::t for string translation and BreadcrumbBuilderBase::l for link generation.
Updates Done (doc team, etc.)
Online documentation: 
Not done
Theming guide: 
Not done
Module developer documentation: 
Not done
Examples project: 
Not done
Coder Review: 
Not done
Coder Upgrade: 
Not done
Other: 
Other updates done