Replace all module_hook() deprecated function calls.

+++ b/core/modules/system/system.moduleundefined
@@ -3167,7 +3167,7 @@ function system_get_module_admin_tasks($module, $info) {
diff --git a/sites/default/default.settings.php b/sites/default/default.settings.php

diff --git a/sites/default/default.settings.php b/sites/default/default.settings.php
old mode 100644
new mode 100755

Careful with including unrelated change...

I'm brand new to core development but the above patch looks good to me. Not sure if it should be recreated to respect the 80 character comment limited as per:

// this can quickly lead to Drupal::moduleHandler()->implementsHook() being called several thousand times

But other than that, looks fine to me.

Only coding standards comments:

+++ b/core/lib/Drupal/Core/Extension/CachedModuleHandler.phpundefined
@@ -99,7 +99,7 @@ public function resetImplementations() {
+    // this can quickly lead to Drupal::moduleHandler()->implementsHook() being called several thousand times

Line too long, wrap to 80 characters. See https://drupal.org/node/1354.

+++ b/core/lib/Drupal/Core/Extension/CachedModuleHandler.phpundefined
@@ -139,7 +139,7 @@ protected function getImplementationInfo($hook) {
+        // Since Drupal::moduleHandler()->implementsHook() may needlessly try to load the include file again,

Same here.

+++ b/core/includes/install.incundefined
@@ -993,7 +993,7 @@ function drupal_requirements_severity(&$requirements) {
+  if (Drupal::moduleHandler()->implementsHook($module, 'requirements')) {
     // Check requirements

ModuleHandler::invoke() already calls implementsHook() and returns NULL if nothing's there, so we should remove it altogether.

+++ b/core/modules/search/search.moduleundefined
@@ -1062,9 +1062,9 @@ function search_box_form_submit($form, &$form_state) {
 function search_data($keys, $module, $conditions = NULL) {
-  if (module_hook($module, 'search_execute')) {
+  if (Drupal::moduleHandler()->implementsHook($module, 'search_execute')) {
     $results = module_invoke($module, 'search_execute', $keys, $conditions);
-    if (module_hook($module, 'search_page')) {
+    if (Drupal::moduleHandler()->implementsHook($module, 'search_page')) {
       return module_invoke($module, 'search_page', $results);

Again this is also checked internally by module_invoke().

Nope, I forgot to change status with #10, then crossposted with #11.

Commited/pushed to 8.x, thanks!