Move ownership of AppSorting from ExtensionPrefs to ExtensionSystem

BUG=None

Review URL: https://codereview.chromium.org/1254363004

Cr-Commit-Position: refs/heads/master@{#342093}
diff --git a/chrome/browser/extensions/extension_service.cc b/chrome/browser/extensions/extension_service.cc
index 1b1ca1f2..88b0a12d 100644
--- a/chrome/browser/extensions/extension_service.cc
+++ b/chrome/browser/extensions/extension_service.cc
@@ -65,6 +65,7 @@
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/browser/storage_partition.h"
+#include "extensions/browser/app_sorting.h"
 #include "extensions/browser/event_router.h"
 #include "extensions/browser/extension_host.h"
 #include "extensions/browser/extension_prefs.h"