Update from https://crrev.com/329939

base/prefs/pref_service.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/prefs/pref_service.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/files/file_path.h"
@@ skipping 20 matching lines @@
       : callback_(cb) {}
 
   void OnError(PersistentPrefStore::PrefReadError error) override {
     callback_.Run(error);
   }
 
  private:
   base::Callback<void(PersistentPrefStore::PrefReadError)> callback_;
 };
 
+// Returns the WriteablePrefStore::PrefWriteFlags for the pref with the given
+// |path|.
+uint32 GetWriteFlags(const PrefService::Preference* pref) {
+  uint32 write_flags = WriteablePrefStore::DEFAULT_PREF_WRITE_FLAGS;
+
+  if (!pref)
+    return write_flags;
+
+  if (pref->registration_flags() & PrefRegistry::LOSSY_PREF)
+    write_flags |= WriteablePrefStore::LOSSY_PREF_WRITE_FLAG;
+  return write_flags;
+}
+
 }  // namespace
 
 PrefService::PrefService(
     PrefNotifierImpl* pref_notifier,
     PrefValueStore* pref_value_store,
     PersistentPrefStore* user_prefs,
     PrefRegistry* pref_registry,
     base::Callback<void(PersistentPrefStore::PrefReadError)>
         read_error_callback,
     bool async)
@@ skipping 119 matching lines @@
 
 bool PrefService::HasPrefPath(const std::string& path) const {
   const Preference* pref = FindPreference(path);
   return pref && !pref->IsDefaultValue();
 }
 
 scoped_ptr<base::DictionaryValue> PrefService::GetPreferenceValues() const {
   DCHECK(CalledOnValidThread());
   scoped_ptr<base::DictionaryValue> out(new base::DictionaryValue);
   for (const auto& it : *pref_registry_) {
-    const base::Value* value = GetPreferenceValue(it.first);
-    out->Set(it.first, value->DeepCopy());
+    out->Set(it.first, GetPreferenceValue(it.first)->CreateDeepCopy());
   }
   return out.Pass();
 }
 
 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()->DeepCopy());
+    out->Set(it.first, pref->GetValue()->CreateDeepCopy());
   }
   return out.Pass();
 }
 
 scoped_ptr<base::DictionaryValue>
 PrefService::GetPreferenceValuesWithoutPathExpansion() const {
   DCHECK(CalledOnValidThread());
   scoped_ptr<base::DictionaryValue> out(new base::DictionaryValue);
   for (const auto& it : *pref_registry_) {
     const base::Value* value = GetPreferenceValue(it.first);
     DCHECK(value);
-    out->SetWithoutPathExpansion(it.first, value->DeepCopy());
+    out->SetWithoutPathExpansion(it.first, value->CreateDeepCopy());
   }
   return out.Pass();
 }
 
 const PrefService::Preference* PrefService::FindPreference(
     const std::string& pref_name) const {
   DCHECK(CalledOnValidThread());
   PreferenceMap::iterator it = prefs_map_.find(pref_name);
   if (it != prefs_map_.end())
     return &(it->second);
@@ skipping 133 matching lines @@
 }
 
 void PrefService::ClearPref(const std::string& path) {
   DCHECK(CalledOnValidThread());
 
   const Preference* pref = FindPreference(path);
   if (!pref) {
     NOTREACHED() << "Trying to clear an unregistered pref: " << path;
     return;
   }
-  user_pref_store_->RemoveValue(path);
+  user_pref_store_->RemoveValue(path, GetWriteFlags(pref));
 }
 
 void PrefService::Set(const std::string& path, const base::Value& value) {
   SetUserPrefValue(path, value.DeepCopy());
 }
 
 void PrefService::SetBoolean(const std::string& path, bool value) {
   SetUserPrefValue(path, new base::FundamentalValue(value));
 }
 
@@ skipping 76 matching lines @@
   base::Value* value = NULL;
   if (!user_pref_store_->GetMutableValue(path, &value) ||
       !value->IsType(type)) {
     if (type == base::Value::TYPE_DICTIONARY) {
       value = new base::DictionaryValue;
     } else if (type == base::Value::TYPE_LIST) {
       value = new base::ListValue;
     } else {
       NOTREACHED();
     }
-    user_pref_store_->SetValueSilently(path, value);
+    user_pref_store_->SetValueSilently(path, value, GetWriteFlags(pref));
   }
   return value;
 }
 
 void PrefService::ReportUserPrefChanged(const std::string& key) {
   DCHECK(CalledOnValidThread());
-  user_pref_store_->ReportValueChanged(key);
+  user_pref_store_->ReportValueChanged(key, GetWriteFlags(FindPreference(key)));
 }
 
 void PrefService::SetUserPrefValue(const std::string& path,
                                    base::Value* new_value) {
   scoped_ptr<base::Value> owned_value(new_value);
   DCHECK(CalledOnValidThread());
 
   const Preference* pref = FindPreference(path);
   if (!pref) {
     NOTREACHED() << "Trying to write an unregistered pref: " << path;
     return;
   }
   if (pref->GetType() != new_value->GetType()) {
     NOTREACHED() << "Trying to set pref " << path
                  << " of type " << pref->GetType()
                  << " to value of type " << new_value->GetType();
     return;
   }
 
-  user_pref_store_->SetValue(path, owned_value.release());
+  user_pref_store_->SetValue(path, owned_value.release(), GetWriteFlags(pref));
 }
 
 void PrefService::UpdateCommandLinePrefStore(PrefStore* command_line_store) {
   pref_value_store_->UpdateCommandLinePrefStore(command_line_store);
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 // PrefService::Preference
 
 PrefService::Preference::Preference(const PrefService* service,
                                     const std::string& name,
                                     base::Value::Type type)
     : name_(name), type_(type), pref_service_(service) {
   DCHECK(service);
+  // Cache the registration flags at creation time to avoid multiple map lookups
+  // later.
+  registration_flags_ = service->pref_registry_->GetRegistrationFlags(name_);
 }
 
 const std::string PrefService::Preference::name() const {
   return name_;
 }
 
 base::Value::Type PrefService::Preference::GetType() const {
   return type_;
 }
 
@@ skipping 76 matching lines @@
       DCHECK(found_value->IsType(default_type));
       return found_value;
     } else {
       // Every registered preference has at least a default value.
       NOTREACHED() << "no valid value found for registered pref " << path;
     }
   }
 
   return NULL;
 }