[Policy Experimental] Add "recommended" policies for URL exceptions.

components/prefs/pref_service.cc

Index: components/prefs/pref_service.cc
diff --git a/components/prefs/pref_service.cc b/components/prefs/pref_service.cc
index 1ef2313b3fa45576e6784ed373609f23725984ef..845bf534f09ce132f6bbecf82e8b482b05f90296 100644
--- a/components/prefs/pref_service.cc
+++ b/components/prefs/pref_service.cc
@@ -538,18 +538,32 @@ const base::Value* PrefService::Preference::GetValue() const {
   return result;
 }
 
+const base::Value* PrefService::Preference::GetManagedValue() const {
+  DCHECK(pref_service_->FindPreference(name_))
+      << "Must register pref before getting its value";
+
+  const base::Value* found_value = nullptr;
+  if (pref_value_store()->GetManagedValue(name_, type_, &found_value)) {
+    DCHECK(found_value->IsType(type_));
+    return found_value;
+  }
+
+  // The pref has no managed value.
+  return nullptr;
+}
+
 const base::Value* PrefService::Preference::GetRecommendedValue() const {
   DCHECK(pref_service_->FindPreference(name_))
       << "Must register pref before getting its value";
 
-  const base::Value* found_value = NULL;
+  const base::Value* found_value = nullptr;
   if (pref_value_store()->GetRecommendedValue(name_, type_, &found_value)) {
     DCHECK(found_value->IsType(type_));
     return found_value;
   }
 
   // The pref has no recommended value.
-  return NULL;
+  return nullptr;
 }
 
 bool PrefService::Preference::IsManaged() const {