Allow whitelisted prefs to be displayed in ChromeOS in chrome://local-state.

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..d9b99ed9456c6e08d444466f6ec8282676528771 100644
--- a/components/prefs/pref_service.cc
+++ b/components/prefs/pref_service.cc
@@ -52,6 +52,15 @@ uint32_t GetWriteFlags(const PrefService::Preference* pref) {
   return write_flags;
 }
 
+bool HasValidPrefix(const std::string& pref_name,
+                    const std::vector<std::string> valid_prefixes) {
+  for (const std::string& prefix : valid_prefixes) {
+    if (pref_name.compare(0, prefix.size(), prefix) == 0)
+      return true;
+  }
+  return false;
+}
+
 }  // namespace
 
 PrefService::PrefService(
@@ -201,15 +210,32 @@ scoped_ptr<base::DictionaryValue> PrefService::GetPreferenceValues() const {
   return out;
 }
 
+void PrefService::SetPreferenceOmitdefault(const std::string& pref_name,
+                                           base::DictionaryValue* out) const {
+  const Preference* pref = FindPreference(pref_name);
+  if (pref->IsDefaultValue())
+    return;
+  out->Set(pref_name, pref->GetValue()->CreateDeepCopy());
+}
+
 scoped_ptr<base::DictionaryValue> PrefService::GetPreferenceValuesOmitDefaults()
     const {
   DCHECK(CalledOnValidThread());
   scoped_ptr<base::DictionaryValue> out(new base::DictionaryValue);
   for (const auto& it : *pref_registry_) {
-    const Preference* pref = FindPreference(it.first);
-    if (pref->IsDefaultValue())
-      continue;
-    out->Set(it.first, pref->GetValue()->CreateDeepCopy());
+    SetPreferenceOmitdefault(it.first, out.get());
+  }
+  return out;
+}
+
+scoped_ptr<base::DictionaryValue>
+PrefService::GetWhitelistedPreferenceValuesOmitDefaults(
+    const std::vector<std::string>& whitelisted_prefixes) const {
+  DCHECK(CalledOnValidThread());
+  scoped_ptr<base::DictionaryValue> out(new base::DictionaryValue);
+  for (const auto& it : *pref_registry_) {
+    if (HasValidPrefix(it.first, whitelisted_prefixes))
+      SetPreferenceOmitdefault(it.first, out.get());
   }
   return out;
 }