Update from https://crrev.com/327068

base/prefs/pref_registry.cc

Index: base/prefs/pref_registry.cc
diff --git a/base/prefs/pref_registry.cc b/base/prefs/pref_registry.cc
index 69f0494f534408807fb916400e2abe45b4cc0107..74f4b5220887ee76e4596e401e806c766d6755c9 100644
--- a/base/prefs/pref_registry.cc
+++ b/base/prefs/pref_registry.cc
@@ -7,6 +7,7 @@
 #include "base/logging.h"
 #include "base/prefs/default_pref_store.h"
 #include "base/prefs/pref_store.h"
+#include "base/stl_util.h"
 #include "base/values.h"
 
 PrefRegistry::PrefRegistry()
@@ -16,6 +17,13 @@ PrefRegistry::PrefRegistry()
 PrefRegistry::~PrefRegistry() {
 }
 
+uint32 PrefRegistry::GetRegistrationFlags(const std::string& pref_name) const {
+  const auto& it = registration_flags_.find(pref_name);
+  if (it == registration_flags_.end())
+    return NO_REGISTRATION_FLAGS;
+  return it->second;
+}
+
 scoped_refptr<PrefStore> PrefRegistry::defaults() {
   return defaults_.get();
 }
@@ -41,13 +49,18 @@ void PrefRegistry::SetDefaultPrefValue(const std::string& pref_name,
 }
 
 void PrefRegistry::RegisterPreference(const std::string& path,
-                                      base::Value* default_value) {
+                                      base::Value* default_value,
+                                      uint32 flags) {
   base::Value::Type orig_type = default_value->GetType();
   DCHECK(orig_type != base::Value::TYPE_NULL &&
          orig_type != base::Value::TYPE_BINARY) <<
          "invalid preference type: " << orig_type;
   DCHECK(!defaults_->GetValue(path, NULL)) <<
       "Trying to register a previously registered pref: " << path;
+  DCHECK(!ContainsKey(registration_flags_, path)) <<
+      "Trying to register a previously registered pref: " << path;
 
   defaults_->SetDefaultValue(path, make_scoped_ptr(default_value));
+  if (flags != NO_REGISTRATION_FLAGS)
+    registration_flags_[path] = flags;
 }