Move required networking pref initialization to helpers.

This reduces a lot of copy/paste pref registration and header
dependencies for network metadata and esim.

This also removes un unnecessary dependency in onc_pref_names.h
on PrefRegistrySyncable.

BUG=None
TEST=All unit tests pass

Change-Id: Ic9ca81be9f7fd9dfedf4cfe9617a2f2871c25669
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3315341
Reviewed-by: Toni Barzic <[email protected]>
Reviewed-by: Kyle Horimoto <[email protected]>
Reviewed-by: Pavol Marko <[email protected]>
Commit-Queue: Steven Bennetts <[email protected]>
Cr-Commit-Position: refs/heads/main@{#949152}
diff --git a/components/onc/onc_pref_names.h b/components/onc/onc_pref_names.h
index 50a1409..8e7f7c9 100644
--- a/components/onc/onc_pref_names.h
+++ b/components/onc/onc_pref_names.h
@@ -9,10 +9,6 @@
 
 class PrefRegistrySimple;
 
-namespace user_prefs {
-class PrefRegistrySyncable;
-}
-
 namespace onc {
 
 namespace prefs {
@@ -25,7 +21,7 @@
 COMPONENT_EXPORT(ONC) void RegisterPrefs(PrefRegistrySimple* registry);
 
 COMPONENT_EXPORT(ONC)
-void RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry);
+void RegisterProfilePrefs(PrefRegistrySimple* registry);
 
 }  // namespace onc