core/MAINTAINERS.txt                               |  4 ++
 core/modules/big_pipe/big_pipe.services.yml        |  7 --
 .../Cache/Context/SessionExistsCacheContext.php    | 70 --------------------
 .../src/Tests/SessionExistsCacheContextTest.php    | 76 ----------------------
 .../session_exists_cache_context_test.info.yml     |  6 --
 .../session_exists_cache_context_test.module       | 24 -------
 6 files changed, 4 insertions(+), 183 deletions(-)

diff --git a/core/MAINTAINERS.txt b/core/MAINTAINERS.txt
index 021f5a4..18caa1d 100644
--- a/core/MAINTAINERS.txt
+++ b/core/MAINTAINERS.txt
@@ -267,6 +267,10 @@ Basic Auth module
 - Klaus Purer 'klausi' https://www.drupal.org/u/klausi
 - Juampy Novillo Requena 'juampy' https://www.drupal.org/u/juampy
 
+BigPipe module
+- Wim Leers 'Wim Leers' https://www.drupal.org/u/wim-leers
+- Fabian Franz 'Fabianx' https://www.drupal.org/u/fabianx
+
 Block module
 - Tim Plunkett 'tim.plunkett' https://www.drupal.org/u/tim.plunkett
 - Ben Dougherty 'benjy' https://www.drupal.org/u/benjy
diff --git a/core/modules/big_pipe/big_pipe.services.yml b/core/modules/big_pipe/big_pipe.services.yml
index cf5ca80..b8ff9d4 100644
--- a/core/modules/big_pipe/big_pipe.services.yml
+++ b/core/modules/big_pipe/big_pipe.services.yml
@@ -18,10 +18,3 @@ services:
     decorates: html_response.attachments_processor
     decoration_inner_name: html_response.attachments_processor.original
     arguments: ['@html_response.attachments_processor.original', '@asset.resolver', '@config.factory', '@asset.css.collection_renderer', '@asset.js.collection_renderer', '@request_stack', '@renderer', '@module_handler']
-
-  # @todo Move this into Drupal 8 core.
-  cache_context.session.exists:
-    class: Drupal\big_pipe\Cache\Context\SessionExistsCacheContext
-    arguments: ['@session_configuration', '@request_stack']
-    tags:
-      - { name: cache.context}
diff --git a/core/modules/big_pipe/src/Cache/Context/SessionExistsCacheContext.php b/core/modules/big_pipe/src/Cache/Context/SessionExistsCacheContext.php
deleted file mode 100644
index f1ca0c9..0000000
--- a/core/modules/big_pipe/src/Cache/Context/SessionExistsCacheContext.php
+++ /dev/null
@@ -1,70 +0,0 @@
-<?php
-
-/**
- * @file
- * Contains \Drupal\big_pipe\Cache\Context\SessionExistsCacheContext.
- */
-
-namespace Drupal\big_pipe\Cache\Context;
-
-use Drupal\Core\Cache\CacheableMetadata;
-use Drupal\Core\Cache\Context\CacheContextInterface;
-use Drupal\Core\Session\SessionConfigurationInterface;
-use Symfony\Component\HttpFoundation\RequestStack;
-
-/**
- * Defines the SessionExistsCacheContext service, for "session or not" caching.
- *
- * Cache context ID: 'session.exists'.
- */
-class SessionExistsCacheContext implements CacheContextInterface {
-
-  /**
-   * The session configuration.
-   *
-   * @var \Drupal\Core\Session\SessionConfigurationInterface
-   */
-  protected $sessionConfiguration;
-
-  /**
-   * The request stack.
-   *
-   * @var \Symfony\Component\HttpFoundation\RequestStack
-   */
-  protected $requestStack;
-
-  /**
-   * Constructs a new SessionExistsCacheContext class.
-   *
-   * @param \Drupal\Core\Session\SessionConfigurationInterface $session_configuration
-   *   The session configuration.
-   * @param \Symfony\Component\HttpFoundation\RequestStack $request_stack
-   *   The request stack.
-   */
-  public function __construct(SessionConfigurationInterface $session_configuration, RequestStack $request_stack) {
-    $this->sessionConfiguration = $session_configuration;
-    $this->requestStack = $request_stack;
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public static function getLabel() {
-    return t('Session exists');
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function getContext() {
-    return $this->sessionConfiguration->hasSession($this->requestStack->getCurrentRequest()) ? '1' : '0';
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function getCacheableMetadata() {
-    return new CacheableMetadata();
-  }
-
-}
diff --git a/core/modules/big_pipe/src/Tests/SessionExistsCacheContextTest.php b/core/modules/big_pipe/src/Tests/SessionExistsCacheContextTest.php
deleted file mode 100644
index 9ca1e89..0000000
--- a/core/modules/big_pipe/src/Tests/SessionExistsCacheContextTest.php
+++ /dev/null
@@ -1,76 +0,0 @@
-<?php
-
-/**
- * @file
- * Contains \Drupal\big_pipe\Tests\SessionExistsCacheContextTest.
- */
-
-namespace Drupal\big_pipe\Tests;
-
-use Drupal\Core\Url;
-use Drupal\simpletest\WebTestBase;
-
-/**
- * Tests the 'session.exists' cache context service.
- *
- * @group Cache
- */
-class SessionExistsCacheContextTest extends WebTestBase {
-
-  /**
-   * Modules to enable.
-   *
-   * @var array
-   */
-  public static $modules = ['big_pipe', 'session_exists_cache_context_test'];
-
-  /**
-   * Tests \Drupal\big_pipe\Cache\Context\SessionExistsCacheContext::getContext().
-   */
-  public function testCacheContext() {
-    $this->dumpHeaders = TRUE;
-
-    // Ignore the <meta> refresh that big_pipe.module sets. It causes a redirect
-    // to a page that sets another cookie, which causes WebTestBase to lose the
-    // session cookie.
-    $this->maximumMetaRefreshCount = 0;
-
-    // 1. No session (anonymous).
-    $this->assertSessionCookieOnClient(FALSE);
-    $this->drupalGet(Url::fromRoute('<front>'));
-    $this->assertSessionCookieOnClient(FALSE);
-    $this->assertRaw('Session does not exist!');
-    $this->assertRaw('[session.exists]=0');
-
-    // 2. Session (authenticated).
-    $this->assertSessionCookieOnClient(FALSE);
-    $this->drupalLogin($this->rootUser);
-    $this->assertSessionCookieOnClient(TRUE);
-    $this->assertRaw('Session exists!');
-    $this->assertRaw('[session.exists]=1');
-    $this->drupalLogout();
-    $this->assertSessionCookieOnClient(FALSE);
-    $this->assertRaw('Session does not exist!');
-    $this->assertRaw('[session.exists]=0');
-
-    // 3. Session (anonymous).
-    $this->assertSessionCookieOnClient(FALSE);
-    $this->drupalGet(Url::fromRoute('<front>', [], ['query' => ['trigger_session' => 1]]));
-    $this->assertSessionCookieOnClient(TRUE);
-    $this->assertRaw('Session does not exist!');
-    $this->assertRaw('[session.exists]=0');
-    $this->drupalGet(Url::fromRoute('<front>'));
-    $this->assertSessionCookieOnClient(TRUE);
-    $this->assertRaw('Session exists!');
-    $this->assertRaw('[session.exists]=1');
-  }
-
-  /**
-   * Asserts whether a session cookie is present on the client or not.
-   */
-  function assertSessionCookieOnClient($expected_present) {
-    $non_deleted_cookies = array_filter($this->cookies, function ($item) { return $item['value'] !== 'deleted'; });
-    $this->assertEqual($expected_present, isset($non_deleted_cookies[$this->getSessionName()]), 'Session cookie exists.');
-  }
-
-}
diff --git a/core/modules/big_pipe/tests/modules/session_exists_cache_context_test/session_exists_cache_context_test.info.yml b/core/modules/big_pipe/tests/modules/session_exists_cache_context_test/session_exists_cache_context_test.info.yml
deleted file mode 100644
index b376a57..0000000
--- a/core/modules/big_pipe/tests/modules/session_exists_cache_context_test/session_exists_cache_context_test.info.yml
+++ /dev/null
@@ -1,6 +0,0 @@
-name: 'session.exists cache context test'
-type: module
-description: 'Support module for session.exists cache context testing.'
-package: Testing
-version: VERSION
-core: 8.x
diff --git a/core/modules/big_pipe/tests/modules/session_exists_cache_context_test/session_exists_cache_context_test.module b/core/modules/big_pipe/tests/modules/session_exists_cache_context_test/session_exists_cache_context_test.module
deleted file mode 100644
index b4179c0..0000000
--- a/core/modules/big_pipe/tests/modules/session_exists_cache_context_test/session_exists_cache_context_test.module
+++ /dev/null
@@ -1,24 +0,0 @@
-<?php
-
-/**
- * Implements hook_page_top().
- */
-function session_exists_cache_context_test_page_top(array &$page_top) {
-  // Ensure this hook is invoked on every page load.
-  $page_top['#cache']['max-age'] = 0;
-
-  $request = \Drupal::request();
-  $session_exists = \Drupal::service('session_configuration')->hasSession($request);
-  $page_top['session_exists_cache_context_test'] = [
-    'label' => [
-      '#markup' => '<p>' . ($session_exists ? 'Session exists!' : 'Session does not exist!') . '</p>',
-    ],
-    'cache_context_value' => [
-      '#markup' => '<code>[session.exists]=' . \Drupal::service('cache_context.session.exists')->getContext() . '</code>',
-    ],
-  ];
-
-  if (\Drupal::request()->query->get('trigger_session')) {
-    $_SESSION['session_exists_cache_context_test'] = TRUE;
-  }
-}