diff --git a/core/modules/shortcut/shortcut.module b/core/modules/shortcut/shortcut.module
index 9ec9e3d..761e7ae 100644
--- a/core/modules/shortcut/shortcut.module
+++ b/core/modules/shortcut/shortcut.module
@@ -713,10 +713,10 @@ function shortcut_preprocess_page(&$variables) {
 }
 
 /**
- * Implements hook_toolbar_register_tabs().
+ * Implements hook_toolbar().
  */
-function shortcut_toolbar_register_tabs() {
-  $tab['shortcuts'] = array(
+function shortcut_toolbar() {
+  $items['shortcuts'] = array(
     'tab' => array(
       'title' => t('Shortcuts'),
       'href' => '',
@@ -730,7 +730,7 @@ function shortcut_toolbar_register_tabs() {
     ),
   );
 
-  return $tab;
+  return $items;
 }
 
 /**
diff --git a/core/modules/toolbar/toolbar.api.php b/core/modules/toolbar/toolbar.api.php
new file mode 100644
index 0000000..783089b
--- /dev/null
+++ b/core/modules/toolbar/toolbar.api.php
@@ -0,0 +1,97 @@
+<?php
+
+// TODO: node.api.php has this line; what is right for this module?
+// use Drupal\Core\Entity\EntityInterface;
+
+/**
+ * @file
+ * Hooks provided by the Toolbar module.
+ */
+
+/**
+ * @addtogroup hooks
+ * @{
+ */
+
+/**
+ * Add items to the Toolbar menu.
+ *
+ * The Toolbar has two parts. The tabs are menu links, rendered by
+ * theme_links(), that are displayed if the module is enabled and the user has
+ * the 'access toolbar' permission. The trays are render elements, usually lists
+ * of links, and each tray corresponds to a tab. When a tab is activated, the
+ * corresponding tray is displayed; only one tab can be activated at a time. If
+ * a tab does not have a corresponding tray, or if javascript is disabled, then
+ * the tab is simply a link.
+ *
+ * This hook is invoked in toolbar_view().
+ *
+ * @return
+ *   An array of toolbar items, keyed by unique identifiers such as 'home' or
+ *   'administration', or the short name of the module implementing the hook.
+ *   The corresponding value is an associative array that may contain the
+ *   following key-value pairs:
+ *   - 'tab': Required, unless the item is adding links to an existing tab. An
+ *   array with keys 'title', 'href', 'html', and 'attributes', as used by
+ *   theme_links(). The 'href' value is ignored unless 'tray' (below) is
+ *   omitted, or if javascript is disabled.
+ *   - 'tray': Optional. A render element that is displayed when the tab is
+ *     activated.
+ *   - 'weight': Optional. Integer weight used for sorting tabs.
+ *
+ * @see toolbar_view()
+ * @ingroup toolbar_tabs
+ */
+function hook_toolbar() {
+  $items = array();
+
+  // The 'Home' tab is a simple link, with no corresponding tray.
+  $items['home'] = array(
+    'tab' => array(
+      'title' => t('Home'),
+      'href' => '<front>',
+      'html' => FALSE,
+      'attributes' => array(
+        'title' => t('Home page'),
+      ),
+    ),
+    'weight' => -10,
+  );
+
+  // Define the tray in a separate function.
+  $items['shortcuts'] = array(
+    'tab' => array(
+      'title' => t('Shortcuts'),
+      'href' => '',
+      'html' => FALSE,
+      'attributes' => array(
+        'title' => t('Shortcuts'),
+      ),
+    ),
+    'tray' => array(
+      '#pre_render' => array('shortcut_toolbar_pre_render'),
+    ),
+  );
+
+  return $items;
+}
+
+/**
+ * Alter the Toolbar menu after hook_toolbar() is invoked.
+ *
+ * This hook is invoked by toolbar_view() immediately after hook_toolbar(). The
+ * toolbar definitions are passed in by reference. Each element of the $items
+ * array is one item returned by a module from hook_toolbar(). Additional items
+ * may be added, or existing items altered.
+ *
+ * @param $items
+ *   Associative array of Toolbar menu definitions returned from hook_toolbar().
+ */
+function hook_toolbar_alter(&$items) {
+  // Move the User tab to the right.
+  $items['user']['weight'] = 5;
+}
+
+/**
+ * @} End of "addtogroup hooks".
+ */
diff --git a/core/modules/toolbar/toolbar.module b/core/modules/toolbar/toolbar.module
index 0b6f1ae..e2dea63 100755
--- a/core/modules/toolbar/toolbar.module
+++ b/core/modules/toolbar/toolbar.module
@@ -110,82 +110,95 @@ function toolbar_system_info_alter(&$info, $file, $type) {
 }
 
 /**
- * Builds the admin menu as a structured array ready for drupal_render().
- *
- * @return
- *   Array of links and settings relating to the admin menu.
+ * Implements hook_toolbar().
  */
-function toolbar_view() {
+function toolbar_toolbar() {
+  $items = array();
 
-  $build = array(
-    '#theme' => 'toolbar',
-    '#attached'=> array(
-      'library' => array(
-        array('toolbar', 'drupal.toolbar'),
+  // The 'Home' tab is a simple link, with no corresponding tray.
+  $items['home'] = array(
+    'tab' => array(
+      'title' => t('Home'),
+      'href' => '<front>',
+      'html' => FALSE,
+      'attributes' => array(
+        'title' => t('Home page'),
       ),
     ),
+    'weight' => -10,
   );
 
-  // Get the configured breakpoint for switch from vertical to horizontal
-  // toolbar presentation.
-  $breakpoints = entity_load('breakpoint_group', 'module.toolbar.toolbar');
-  if (!empty($breakpoints)) {
-    $build['#attached']['js'] = array(
-        array(
-        'data' => array(
-          'toolbar' => array(
-            'breakpoints' => array(),
-          ),
-        ),
-        'type' => 'setting',
-      )
-    );
-    // // Load the breakpoints for toolbar.
-    foreach ($breakpoints->breakpoints as $key => $breakpoint) {
-      $build['#attached']['js'][0]['data']['toolbar']['breakpoints'][$key] = $breakpoint->mediaQuery;
-    }
-  }
-
-  // Build the default toolbar navigation links.
   // Retrieve the administration menu from the database.
   $tree = toolbar_get_menu_tree();
+
   // Add attributes to the links before rendering.
   toolbar_menu_navigation_links($tree);
+
+  $menu = array();
   $menu['toolbar_administration'] = array(
     '#type' => 'container',
     '#attributes' => array(
-      'class' => array('interactive-menu toolbar-list'),
+      'class' => array('interactive-menu', 'toolbar-list'),
     ),
+    'administration_menu' => menu_tree_output($tree),
   );
-  $menu['toolbar_administration']['administration_menu'] = menu_tree_output($tree);
-
-  $toolbar_groups = array(
-    'home' => array(
-      'tab' => array(
-        'title' => t('Home'),
-        'href' => '<front>',
-        'html' => FALSE,
-      ),
-    ),
-    'administration' => array(
-      'tab' => array(
-        'title' => t('Menu'),
-        'href' => '',
-        'html' => FALSE,
+
+  $items['administration'] = array(
+    'tab' => array(
+      'title' => t('Menu'),
+      'href' => '',
+      'html' => FALSE,
+      'attributes' => array(
+        'title' => t('Admin menu'),
       ),
-      'tray' => $menu,
     ),
+    'tray' => $menu,
+    'weight' => -5,
   );
 
-  // Get groups from other modules.
-  $toolbar_groups = array_merge($toolbar_groups, module_invoke_all('toolbar_register_tabs'));
+  return $items;
+}
 
-  // Bar tabs.
+/**
+ * Builds the admin menu as a structured array ready for drupal_render().
+ *
+ * @return
+ *   Array of links and settings relating to the admin menu.
+ */
+function toolbar_view() {
+
+  $build = array('#theme' => 'toolbar');
+  $build['#attached']['library'][] = array('toolbar', 'drupal.toolbar');
+
+  // Get the configured breakpoint for switch from vertical to horizontal
+  // toolbar presentation.
+  $breakpoints = entity_load('breakpoint_group', 'module.toolbar.toolbar');
+  if (!empty($breakpoints)) {
+    $media_queries = array();
+    $media_queries['toolbar']['breakpoints'] = array_map(
+      function($object) {return $object->mediaQuery;},
+      $breakpoints->breakpoints);
+
+    $build['#attached']['js'] = array();
+    $build['#attached']['js'][] = array(
+      'data' => $media_queries,
+      'type' => 'setting',
+    );
+  }
+
+  // Get groups from all modules that implement hook_toolbar() or
+  // hook_toolbar_alter().
+  $toolbar_groups = module_invoke_all('toolbar');
+  drupal_alter('toolbar', $toolbar_groups);
+  uasort($toolbar_groups, 'drupal_sort_weight');
+
+  // Build the tabs and trays from the toolbar groups.
   $toolbar_tabs = array();
   $toolbar_trays = array();
   foreach ($toolbar_groups as $category => $components) {
     if (!empty($components['tab'])) {
-      // Provide a data attribute to each bar link that associates it with its tray.
+      // Provide a data attribute to each bar link that associates it with its
+      // tray.
       $components['tab']['attributes']['data-toolbar-tray'] = $category;
       if (!isset($components['tab']['attributes']['class'])) {
         $components['tab']['attributes']['class'] = array();
@@ -208,7 +221,8 @@ function toolbar_view() {
     ),
     '#heading' => array('text' => t('Drupal toolbar'), 'level' => 'h2', 'class' => 'element-invisible'),
   );
-  //// Assign the tabs to the build.
+
+  // Assign the trays to the build.
   $build['toolbar_trays'] = array(
     '#theme' => 'toolbar_tray',
     '#trays' => $toolbar_trays,
diff --git a/core/modules/user/user.module b/core/modules/user/user.module
index 61e96cd..fa1a0a5 100644
--- a/core/modules/user/user.module
+++ b/core/modules/user/user.module
@@ -3070,23 +3070,26 @@ function user_file_download_access($field, EntityInterface $entity, File $file)
 }
 
 /**
- * Implements hook_toolbar_register_tabs().
+ * Implements hook_toolbar().
  */
-function user_toolbar_register_tabs() {
+function user_toolbar() {
   global $user;
 
-  $tab['user'] = array(
+  $items['user'] = array(
     'tab' => array(
       'title' => user_format_name($user),
       'href' => '',
       'html' => FALSE,
+      'attributes' => array(
+        'title' => t('My account'),
+      ),
     ),
     'tray' => array(
       '#pre_render' => array('user_toolbar_pre_render'),
     ),
   );
 
-  return $tab;
+  return $items;
 }
 
 /**