Pref service: add support for tracked prefs.

services/preferences/public/cpp/BUILD.gn

Index: services/preferences/public/cpp/BUILD.gn
diff --git a/services/preferences/public/cpp/BUILD.gn b/services/preferences/public/cpp/BUILD.gn
index 09ac205a99bfdeadb17da8bf705ecbf3f25a9153..328ebabc9d360a273b0275ebd3f1b7c943b7d96e 100644
--- a/services/preferences/public/cpp/BUILD.gn
+++ b/services/preferences/public/cpp/BUILD.gn
@@ -18,11 +18,14 @@ source_set("cpp") {
     "pref_store_impl.h",
     "pref_store_manager_impl.cc",
     "pref_store_manager_impl.h",
+    "tracked_persistent_pref_store_factory.cc",
+    "tracked_persistent_pref_store_factory.h",
   ]
 
   public_deps = [
     "//base",
-    "//components/prefs:prefs",
+    "//components/prefs",
+    "//components/user_prefs/tracked:user_prefs_tracked",
     "//services/preferences/public/interfaces",
     "//services/service_manager/public/cpp",
   ]
@@ -31,4 +34,6 @@ source_set("cpp") {
     "//mojo/public/cpp/bindings:bindings",
     "//services/preferences",
   ]
+
+  allow_circular_includes_from = [ "//services/preferences" ]
 }