core/modules/book/book.services.yml                |  2 +-
 .../book/src/Cache/BookNavigationCacheContext.php  | 22 ++++++++--------------
 2 files changed, 9 insertions(+), 15 deletions(-)

diff --git a/core/modules/book/book.services.yml b/core/modules/book/book.services.yml
index 8f7384d..440d021 100644
--- a/core/modules/book/book.services.yml
+++ b/core/modules/book/book.services.yml
@@ -25,6 +25,6 @@ services:
       - { name: access_check, applies_to: _access_book_removable }
   cache_context.book.navigation:
     class: Drupal\book\Cache\BookNavigationCacheContext
-    arguments: ['@book.manager', '@request_stack']
+    arguments: ['@request_stack']
     tags:
       - { name: cache.context}
diff --git a/core/modules/book/src/Cache/BookNavigationCacheContext.php b/core/modules/book/src/Cache/BookNavigationCacheContext.php
index 516bd07..531611f 100644
--- a/core/modules/book/src/Cache/BookNavigationCacheContext.php
+++ b/core/modules/book/src/Cache/BookNavigationCacheContext.php
@@ -7,8 +7,8 @@
 
 namespace Drupal\book\Cache;
 
-use Drupal\book\BookManagerInterface;
 use Drupal\Core\Cache\CacheContextInterface;
+use Symfony\Component\DependencyInjection\ContainerAware;
 use Symfony\Component\HttpFoundation\RequestStack;
 
 /**
@@ -17,15 +17,11 @@
  * This allows for book navigation location-aware caching. It depends on:
  * - whether the current route represents a book node at all
  * - and if so, where in the book hierarchy we are
+ *
+ * This class is container-aware to avoid initializing the 'book.manager'
+ * service when it is not necessary.
  */
-class BookNavigationCacheContext implements CacheContextInterface {
-
-  /**
-   * The book manager.
-   *
-   * @var \Drupal\book\BookManagerInterface
-   */
-  protected $bookManager;
+class BookNavigationCacheContext extends ContainerAware implements CacheContextInterface {
 
   /**
    * The request stack.
@@ -37,13 +33,10 @@ class BookNavigationCacheContext implements CacheContextInterface {
   /**
    * Constructs a new BookNavigationCacheContext service.
    *
-   * @param \Drupal\book\BookManagerInterface $book_manager
-   *   The book manager.
    * @param \Symfony\Component\HttpFoundation\RequestStack $request_stack
    *   The request stack.
    */
-  public function __construct(BookManagerInterface $book_manager, RequestStack $request_stack) {
-    $this->bookManager = $book_manager;
+  public function __construct(RequestStack $request_stack) {
     $this->requestStack = $request_stack;
   }
 
@@ -70,7 +63,8 @@ public function getContext() {
     }
 
     // If we're looking at a book node, get the trail for that node.
-    $active_trail = $this->bookManager->getActiveTrailIds($node->book['bid'], $node->book);
+    $active_trail = $this->container->get('book.manager')
+      ->getActiveTrailIds($node->book['bid'], $node->book);
     return 'book.' . implode('|', $active_trail);
   }