root/chrome/browser/prefs/pref_model_associator.cc

DEFINITIONS

1. GetSpecifics
2. GetMutableSpecifics
3. GetOldMigratedPreferenceName
4. GetNewMigratedPreferenceName
5. type_
6. InitPrefAndAssociate
7. MergeDataAndStartSyncing
8. StopSyncing
9. MergePreference
10. CreatePrefSyncData
11. MergeListValues
12. MergeDictionaryValues
13. IsMigratedPreference
14. IsOldMigratedPreference
15. GetAllSyncData
16. ProcessSyncChanges
17. ReadPreferenceSpecifics
18. IsPrefSynced
19. AddSyncedPrefObserver
20. RemoveSyncedPrefObserver
21. registered_preferences
22. RegisterPref
23. IsPrefRegistered
24. ProcessPrefChange
25. SetPrefService
26. NotifySyncedPrefObservers

// 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 "chrome/browser/prefs/pref_model_associator.h"

#include "base/auto_reset.h"
#include "base/json/json_reader.h"
#include "base/json/json_string_value_serializer.h"
#include "base/location.h"
#include "base/logging.h"
#include "base/prefs/pref_service.h"
#include "base/stl_util.h"
#include "base/strings/utf_string_conversions.h"
#include "base/values.h"
#include "chrome/browser/chrome_notification_types.h"
#include "chrome/browser/prefs/pref_service_syncable.h"
#include "chrome/common/pref_names.h"
#include "sync/api/sync_change.h"
#include "sync/api/sync_error_factory.h"
#include "sync/protocol/preference_specifics.pb.h"
#include "sync/protocol/sync.pb.h"

using syncer::PREFERENCES;
using syncer::PRIORITY_PREFERENCES;

namespace {

const sync_pb::PreferenceSpecifics& GetSpecifics(const syncer::SyncData& pref) {
  DCHECK(pref.GetDataType() == syncer::PREFERENCES ||
         pref.GetDataType() == syncer::PRIORITY_PREFERENCES);
  if (pref.GetDataType() == syncer::PRIORITY_PREFERENCES) {
    return pref.GetSpecifics().priority_preference().preference();
  } else {
    return pref.GetSpecifics().preference();
  }
}

sync_pb::PreferenceSpecifics* GetMutableSpecifics(
    const syncer::ModelType type,
    sync_pb::EntitySpecifics* specifics) {
  if (type == syncer::PRIORITY_PREFERENCES) {
    DCHECK(!specifics->has_preference());
    return specifics->mutable_priority_preference()->mutable_preference();
  } else {
    DCHECK(!specifics->has_priority_preference());
    return specifics->mutable_preference();
  }
}

// List of migrated preference name pairs. If a preference is migrated
// (meaning renamed) adding the old and new preference names here will ensure
// that the sync engine knows how to deal with the synced values coming in
// with the old name. Preference migration itself doesn't happen here. It may
// happen in session_startup_pref.cc.
const struct MigratedPreferences {
  const char* const old_name;
  const char* const new_name;
} kMigratedPreferences[] = {
  { prefs::kURLsToRestoreOnStartupOld, prefs::kURLsToRestoreOnStartup },
};

std::string GetOldMigratedPreferenceName(const char* preference_name) {
  for (size_t i = 0; i < arraysize(kMigratedPreferences); ++i) {
    if (!strcmp(kMigratedPreferences[i].new_name, preference_name))
      return kMigratedPreferences[i].old_name;
  }
  return std::string();
}

std::string GetNewMigratedPreferenceName(const char* old_preference_name) {
  for (size_t i = 0; i < arraysize(kMigratedPreferences); ++i) {
    if (!strcmp(kMigratedPreferences[i].old_name, old_preference_name))
      return kMigratedPreferences[i].new_name;
  }
  return std::string();
}

}  // namespace

PrefModelAssociator::PrefModelAssociator(syncer::ModelType type)
    : models_associated_(false),
      processing_syncer_changes_(false),
      pref_service_(NULL),
      type_(type) {
  DCHECK(CalledOnValidThread());
  DCHECK(type_ == PREFERENCES || type_ == PRIORITY_PREFERENCES);
}

PrefModelAssociator::~PrefModelAssociator() {
  DCHECK(CalledOnValidThread());
  pref_service_ = NULL;

  STLDeleteContainerPairSecondPointers(synced_pref_observers_.begin(),
                                       synced_pref_observers_.end());
  synced_pref_observers_.clear();
}

void PrefModelAssociator::InitPrefAndAssociate(
    const syncer::SyncData& sync_pref,
    const std::string& pref_name,
    syncer::SyncChangeList* sync_changes,
    SyncDataMap* migrated_preference_list) {
  const base::Value* user_pref_value = pref_service_->GetUserPrefValue(
      pref_name.c_str());
  VLOG(1) << "Associating preference " << pref_name;

  if (sync_pref.IsValid()) {
    const sync_pb::PreferenceSpecifics& preference = GetSpecifics(sync_pref);
    DCHECK(pref_name == preference.name() ||
           (IsMigratedPreference(pref_name.c_str()) &&
            preference.name() ==
                GetOldMigratedPreferenceName(pref_name.c_str())));
    base::JSONReader reader;
    scoped_ptr<base::Value> sync_value(reader.ReadToValue(preference.value()));
    if (!sync_value.get()) {
      LOG(ERROR) << "Failed to deserialize preference value: "
                 << reader.GetErrorMessage();
      return;
    }

    if (user_pref_value) {
      DVLOG(1) << "Found user pref value for " << pref_name;
      // We have both server and local values. Merge them.
      scoped_ptr<base::Value> new_value(
          MergePreference(pref_name, *user_pref_value, *sync_value));

      // Update the local preference based on what we got from the
      // sync server. Note: this only updates the user value store, which is
      // ignored if the preference is policy controlled.
      if (new_value->IsType(base::Value::TYPE_NULL)) {
        LOG(WARNING) << "Sync has null value for pref " << pref_name.c_str();
        pref_service_->ClearPref(pref_name.c_str());
      } else if (!new_value->IsType(user_pref_value->GetType())) {
        LOG(WARNING) << "Synced value for " << preference.name()
                     << " is of type " << new_value->GetType()
                     << " which doesn't match pref type "
                     << user_pref_value->GetType();
      } else if (!user_pref_value->Equals(new_value.get())) {
        pref_service_->Set(pref_name.c_str(), *new_value);
      }

      // If the merge resulted in an updated value, inform the syncer.
      if (!sync_value->Equals(new_value.get())) {
        syncer::SyncData sync_data;
        if (!CreatePrefSyncData(pref_name, *new_value, &sync_data)) {
          LOG(ERROR) << "Failed to update preference.";
          return;
        }

        if (IsMigratedPreference(pref_name.c_str())) {
          // This preference has been migrated from an old version that must be
          // kept in sync on older versions of Chrome.
          std::string old_pref_name =
              GetOldMigratedPreferenceName(pref_name.c_str());

          if (preference.name() == old_pref_name) {
            DCHECK(migrated_preference_list);
            // If the name the syncer has is the old pre-migration value, then
            // it's possible the new migrated preference name hasn't been synced
            // yet. In that case the SyncChange should be an ACTION_ADD rather
            // than an ACTION_UPDATE. Defer the decision of whether to sync with
            // ACTION_ADD or ACTION_UPDATE until the migrated_preferences phase.
            if (migrated_preference_list)
              (*migrated_preference_list)[pref_name] = sync_data;
          } else {
            DCHECK_EQ(preference.name(), pref_name);
            sync_changes->push_back(
                syncer::SyncChange(FROM_HERE,
                                   syncer::SyncChange::ACTION_UPDATE,
                                   sync_data));
          }

          syncer::SyncData old_sync_data;
          if (!CreatePrefSyncData(old_pref_name, *new_value, &old_sync_data)) {
            LOG(ERROR) << "Failed to update preference.";
            return;
          }
          if (migrated_preference_list)
            (*migrated_preference_list)[old_pref_name] = old_sync_data;
        } else {
          sync_changes->push_back(
            syncer::SyncChange(FROM_HERE,
                               syncer::SyncChange::ACTION_UPDATE,
                               sync_data));
        }
      }
    } else if (!sync_value->IsType(base::Value::TYPE_NULL)) {
      // Only a server value exists. Just set the local user value.
      pref_service_->Set(pref_name.c_str(), *sync_value);
    } else {
      LOG(WARNING) << "Sync has null value for pref " << pref_name.c_str();
    }
    synced_preferences_.insert(preference.name());
  } else if (user_pref_value) {
    // The server does not know about this preference and should be added
    // to the syncer's database.
    syncer::SyncData sync_data;
    if (!CreatePrefSyncData(pref_name, *user_pref_value, &sync_data)) {
      LOG(ERROR) << "Failed to update preference.";
      return;
    }
    sync_changes->push_back(
        syncer::SyncChange(FROM_HERE,
                           syncer::SyncChange::ACTION_ADD,
                           sync_data));
    synced_preferences_.insert(pref_name);
  }

  // Else this pref does not have a sync value but also does not have a user
  // controlled value (either it's a default value or it's policy controlled,
  // either way it's not interesting). We can ignore it. Once it gets changed,
  // we'll send the new user controlled value to the syncer.
}

syncer::SyncMergeResult PrefModelAssociator::MergeDataAndStartSyncing(
    syncer::ModelType type,
    const syncer::SyncDataList& initial_sync_data,
    scoped_ptr<syncer::SyncChangeProcessor> sync_processor,
    scoped_ptr<syncer::SyncErrorFactory> sync_error_factory) {
  DCHECK_EQ(type_, type);
  DCHECK(CalledOnValidThread());
  DCHECK(pref_service_);
  DCHECK(!sync_processor_.get());
  DCHECK(sync_processor.get());
  DCHECK(sync_error_factory.get());
  syncer::SyncMergeResult merge_result(type);
  sync_processor_ = sync_processor.Pass();
  sync_error_factory_ = sync_error_factory.Pass();

  syncer::SyncChangeList new_changes;
  std::set<std::string> remaining_preferences = registered_preferences_;

  // Maintains a list of old migrated preference names that we wish to sync.
  // Keep track of these in a list such that when the preference iteration
  // loops below are complete we can go back and determine whether
  SyncDataMap migrated_preference_list;

  // Go through and check for all preferences we care about that sync already
  // knows about.
  for (syncer::SyncDataList::const_iterator sync_iter =
           initial_sync_data.begin();
       sync_iter != initial_sync_data.end();
       ++sync_iter) {
    DCHECK_EQ(type_, sync_iter->GetDataType());

    const sync_pb::PreferenceSpecifics& preference = GetSpecifics(*sync_iter);
    std::string sync_pref_name = preference.name();

    if (remaining_preferences.count(sync_pref_name) == 0) {
      if (IsOldMigratedPreference(sync_pref_name.c_str())) {
        // This old pref name is not syncable locally anymore but we accept
        // changes from other Chrome installs of previous versions and migrate
        // them to the new name. Note that we will be merging any differences
        // between the new and old values and sync'ing them back.
        sync_pref_name = GetNewMigratedPreferenceName(sync_pref_name.c_str());
      } else {
        // We're not syncing this preference locally, ignore the sync data.
        // TODO(zea): Eventually we want to be able to have the syncable service
        // reconstruct all sync data for its datatype (therefore having
        // GetAllSyncData be a complete representation). We should store this
        // data somewhere, even if we don't use it.
        continue;
      }
    } else {
      remaining_preferences.erase(sync_pref_name);
    }
    InitPrefAndAssociate(*sync_iter, sync_pref_name, &new_changes,
                         &migrated_preference_list);
  }

  // Go through and build sync data for any remaining preferences.
  for (std::set<std::string>::iterator pref_name_iter =
          remaining_preferences.begin();
       pref_name_iter != remaining_preferences.end();
       ++pref_name_iter) {
    InitPrefAndAssociate(syncer::SyncData(), *pref_name_iter, &new_changes,
                         &migrated_preference_list);
  }

  // Now go over any migrated preference names and build sync data for them too.
  for (SyncDataMap::const_iterator migrated_pref_iter =
          migrated_preference_list.begin();
       migrated_pref_iter != migrated_preference_list.end();
       ++migrated_pref_iter) {
    syncer::SyncChange::SyncChangeType change_type =
        (synced_preferences_.count(migrated_pref_iter->first) == 0) ?
            syncer::SyncChange::ACTION_ADD :
            syncer::SyncChange::ACTION_UPDATE;
    new_changes.push_back(
        syncer::SyncChange(FROM_HERE, change_type, migrated_pref_iter->second));
    synced_preferences_.insert(migrated_pref_iter->first);
  }

  // Push updates to sync.
  merge_result.set_error(
      sync_processor_->ProcessSyncChanges(FROM_HERE, new_changes));
  if (merge_result.error().IsSet())
    return merge_result;

  models_associated_ = true;
  pref_service_->OnIsSyncingChanged();
  return merge_result;
}

void PrefModelAssociator::StopSyncing(syncer::ModelType type) {
  DCHECK_EQ(type_, type);
  models_associated_ = false;
  sync_processor_.reset();
  sync_error_factory_.reset();
  pref_service_->OnIsSyncingChanged();
}

scoped_ptr<base::Value> PrefModelAssociator::MergePreference(
    const std::string& name,
    const base::Value& local_value,
    const base::Value& server_value) {
  // This function special cases preferences individually, so don't attempt
  // to merge for all migrated values.
  if (name == prefs::kURLsToRestoreOnStartup ||
      name == prefs::kURLsToRestoreOnStartupOld) {
    return scoped_ptr<base::Value>(
        MergeListValues(local_value, server_value)).Pass();
  }

  if (name == prefs::kContentSettingsPatternPairs) {
    return scoped_ptr<base::Value>(
        MergeDictionaryValues(local_value, server_value)).Pass();
  }

  // If this is not a specially handled preference, server wins.
  return scoped_ptr<base::Value>(server_value.DeepCopy()).Pass();
}

bool PrefModelAssociator::CreatePrefSyncData(
    const std::string& name,
    const base::Value& value,
    syncer::SyncData* sync_data) const {
  if (value.IsType(base::Value::TYPE_NULL)) {
    LOG(ERROR) << "Attempting to sync a null pref value for " << name;
    return false;
  }

  std::string serialized;
  // TODO(zea): consider JSONWriter::Write since you don't have to check
  // failures to deserialize.
  JSONStringValueSerializer json(&serialized);
  if (!json.Serialize(value)) {
    LOG(ERROR) << "Failed to serialize preference value.";
    return false;
  }

  sync_pb::EntitySpecifics specifics;
  sync_pb::PreferenceSpecifics* pref_specifics =
      GetMutableSpecifics(type_, &specifics);

  pref_specifics->set_name(name);
  pref_specifics->set_value(serialized);
  *sync_data = syncer::SyncData::CreateLocalData(name, name, specifics);
  return true;
}

base::Value* PrefModelAssociator::MergeListValues(const base::Value& from_value,
                                                  const base::Value& to_value) {
  if (from_value.GetType() == base::Value::TYPE_NULL)
    return to_value.DeepCopy();
  if (to_value.GetType() == base::Value::TYPE_NULL)
    return from_value.DeepCopy();

  DCHECK(from_value.GetType() == base::Value::TYPE_LIST);
  DCHECK(to_value.GetType() == base::Value::TYPE_LIST);
  const base::ListValue& from_list_value =
      static_cast<const base::ListValue&>(from_value);
  const base::ListValue& to_list_value =
      static_cast<const base::ListValue&>(to_value);
  base::ListValue* result = to_list_value.DeepCopy();

  for (base::ListValue::const_iterator i = from_list_value.begin();
       i != from_list_value.end(); ++i) {
    base::Value* value = (*i)->DeepCopy();
    result->AppendIfNotPresent(value);
  }
  return result;
}

base::Value* PrefModelAssociator::MergeDictionaryValues(
    const base::Value& from_value,
    const base::Value& to_value) {
  if (from_value.GetType() == base::Value::TYPE_NULL)
    return to_value.DeepCopy();
  if (to_value.GetType() == base::Value::TYPE_NULL)
    return from_value.DeepCopy();

  DCHECK_EQ(from_value.GetType(), base::Value::TYPE_DICTIONARY);
  DCHECK_EQ(to_value.GetType(), base::Value::TYPE_DICTIONARY);
  const base::DictionaryValue& from_dict_value =
      static_cast<const base::DictionaryValue&>(from_value);
  const base::DictionaryValue& to_dict_value =
      static_cast<const base::DictionaryValue&>(to_value);
  base::DictionaryValue* result = to_dict_value.DeepCopy();

  for (base::DictionaryValue::Iterator it(from_dict_value); !it.IsAtEnd();
       it.Advance()) {
    const base::Value* from_value = &it.value();
    base::Value* to_key_value;
    if (result->GetWithoutPathExpansion(it.key(), &to_key_value)) {
      if (to_key_value->GetType() == base::Value::TYPE_DICTIONARY) {
        base::Value* merged_value =
            MergeDictionaryValues(*from_value, *to_key_value);
        result->SetWithoutPathExpansion(it.key(), merged_value);
      }
      // Note that for all other types we want to preserve the "to"
      // values so we do nothing here.
    } else {
      result->SetWithoutPathExpansion(it.key(), from_value->DeepCopy());
    }
  }
  return result;
}

// static
bool PrefModelAssociator::IsMigratedPreference(const char* preference_name) {
  return !GetOldMigratedPreferenceName(preference_name).empty();
}

// static
bool PrefModelAssociator::IsOldMigratedPreference(
    const char* old_preference_name) {
  return !GetNewMigratedPreferenceName(old_preference_name).empty();
}

// Note: This will build a model of all preferences registered as syncable
// with user controlled data. We do not track any information for preferences
// not registered locally as syncable and do not inform the syncer of
// non-user controlled preferences.
syncer::SyncDataList PrefModelAssociator::GetAllSyncData(
    syncer::ModelType type)
    const {
  DCHECK_EQ(type_, type);
  syncer::SyncDataList current_data;
  for (PreferenceSet::const_iterator iter = synced_preferences_.begin();
       iter != synced_preferences_.end();
       ++iter) {
    std::string name = *iter;
    const PrefService::Preference* pref =
      pref_service_->FindPreference(name.c_str());
    DCHECK(pref);
    if (!pref->IsUserControlled() || pref->IsDefaultValue())
      continue;  // This is not data we care about.
    // TODO(zea): plumb a way to read the user controlled value.
    syncer::SyncData sync_data;
    if (!CreatePrefSyncData(name, *pref->GetValue(), &sync_data))
      continue;
    current_data.push_back(sync_data);
  }
  return current_data;
}

syncer::SyncError PrefModelAssociator::ProcessSyncChanges(
    const tracked_objects::Location& from_here,
    const syncer::SyncChangeList& change_list) {
  if (!models_associated_) {
    syncer::SyncError error(FROM_HERE,
                            syncer::SyncError::DATATYPE_ERROR,
                            "Models not yet associated.",
                            PREFERENCES);
    return error;
  }
  base::AutoReset<bool> processing_changes(&processing_syncer_changes_, true);
  syncer::SyncChangeList::const_iterator iter;
  for (iter = change_list.begin(); iter != change_list.end(); ++iter) {
    DCHECK_EQ(type_, iter->sync_data().GetDataType());

    std::string name;
    const sync_pb::PreferenceSpecifics& pref_specifics =
        GetSpecifics(iter->sync_data());

    scoped_ptr<base::Value> value(ReadPreferenceSpecifics(pref_specifics,
                                                          &name));

    if (iter->change_type() == syncer::SyncChange::ACTION_DELETE) {
      // We never delete preferences.
      NOTREACHED() << "Attempted to process sync delete change for " << name
                   << ". Skipping.";
      continue;
    }

    // Skip values we can't deserialize.
    // TODO(zea): consider taking some further action such as erasing the bad
    // data.
    if (!value.get())
      continue;

    // It is possible that we may receive a change to a preference we do not
    // want to sync. For example if the user is syncing a Mac client and a
    // Windows client, the Windows client does not support
    // kConfirmToQuitEnabled. Ignore updates from these preferences.
    const char* pref_name = name.c_str();
    std::string new_name;
    // We migrated this preference name, so do as if the name had not changed.
    if (IsOldMigratedPreference(pref_name)) {
      new_name = GetNewMigratedPreferenceName(pref_name);
      pref_name = new_name.c_str();
    }

    if (!IsPrefRegistered(pref_name))
      continue;

    const PrefService::Preference* pref =
        pref_service_->FindPreference(pref_name);
    DCHECK(pref);

    // This will only modify the user controlled value store, which takes
    // priority over the default value but is ignored if the preference is
    // policy controlled.
    pref_service_->Set(pref_name, *value);

    NotifySyncedPrefObservers(name, true /*from_sync*/);

    // Keep track of any newly synced preferences.
    if (iter->change_type() == syncer::SyncChange::ACTION_ADD) {
      synced_preferences_.insert(name);
    }
  }
  return syncer::SyncError();
}

base::Value* PrefModelAssociator::ReadPreferenceSpecifics(
    const sync_pb::PreferenceSpecifics& preference,
    std::string* name) {
  base::JSONReader reader;
  scoped_ptr<base::Value> value(reader.ReadToValue(preference.value()));
  if (!value.get()) {
    std::string err = "Failed to deserialize preference value: " +
        reader.GetErrorMessage();
    LOG(ERROR) << err;
    return NULL;
  }
  *name = preference.name();
  return value.release();
}

bool PrefModelAssociator::IsPrefSynced(const std::string& name) const {
  return synced_preferences_.find(name) != synced_preferences_.end();
}

void PrefModelAssociator::AddSyncedPrefObserver(const std::string& name,
    SyncedPrefObserver* observer) {
  SyncedPrefObserverList* observers = synced_pref_observers_[name];
  if (observers == NULL) {
    observers = new SyncedPrefObserverList;
    synced_pref_observers_[name] = observers;
  }
  observers->AddObserver(observer);
}

void PrefModelAssociator::RemoveSyncedPrefObserver(const std::string& name,
    SyncedPrefObserver* observer) {
  SyncedPrefObserverMap::iterator observer_iter =
      synced_pref_observers_.find(name);
  if (observer_iter == synced_pref_observers_.end())
    return;
  SyncedPrefObserverList* observers = observer_iter->second;
  observers->RemoveObserver(observer);
}

std::set<std::string> PrefModelAssociator::registered_preferences() const {
  return registered_preferences_;
}

void PrefModelAssociator::RegisterPref(const char* name) {
  DCHECK(!models_associated_ && registered_preferences_.count(name) == 0);
  registered_preferences_.insert(name);
}

bool PrefModelAssociator::IsPrefRegistered(const char* name) {
  return registered_preferences_.count(name) > 0;
}

void PrefModelAssociator::ProcessPrefChange(const std::string& name) {
  if (processing_syncer_changes_)
    return;  // These are changes originating from us, ignore.

  // We only process changes if we've already associated models.
  if (!models_associated_)
    return;

  const PrefService::Preference* preference =
      pref_service_->FindPreference(name.c_str());
  if (!preference)
    return;

  if (!IsPrefRegistered(name.c_str()))
    return;  // We are not syncing this preference.

  syncer::SyncChangeList changes;

  if (!preference->IsUserModifiable()) {
    // If the preference is no longer user modifiable, it must now be controlled
    // by policy, whose values we do not sync. Just return. If the preference
    // stops being controlled by policy, it will revert back to the user value
    // (which we continue to update with sync changes).
    return;
  }

  base::AutoReset<bool> processing_changes(&processing_syncer_changes_, true);

  NotifySyncedPrefObservers(name, false /*from_sync*/);

  if (synced_preferences_.count(name) == 0) {
    // Not in synced_preferences_ means no synced data. InitPrefAndAssociate(..)
    // will determine if we care about its data (e.g. if it has a default value
    // and hasn't been changed yet we don't) and take care syncing any new data.
    InitPrefAndAssociate(syncer::SyncData(), name, &changes, NULL);
  } else {
    // We are already syncing this preference, just update it's sync node.
    syncer::SyncData sync_data;
    if (!CreatePrefSyncData(name, *preference->GetValue(), &sync_data)) {
      LOG(ERROR) << "Failed to update preference.";
      return;
    }
    changes.push_back(
        syncer::SyncChange(FROM_HERE,
                           syncer::SyncChange::ACTION_UPDATE,
                           sync_data));
    // This preference has been migrated from an old version that must be kept
    // in sync on older versions of Chrome.
    if (IsMigratedPreference(name.c_str())) {
      std::string old_pref_name = GetOldMigratedPreferenceName(name.c_str());
      if (!CreatePrefSyncData(old_pref_name,
                              *preference->GetValue(),
                              &sync_data)) {
        LOG(ERROR) << "Failed to update preference.";
        return;
      }

      syncer::SyncChange::SyncChangeType change_type =
          (synced_preferences_.count(old_pref_name) == 0) ?
              syncer::SyncChange::ACTION_ADD :
              syncer::SyncChange::ACTION_UPDATE;
      changes.push_back(
          syncer::SyncChange(FROM_HERE, change_type, sync_data));
    }
  }

  syncer::SyncError error =
      sync_processor_->ProcessSyncChanges(FROM_HERE, changes);
}

void PrefModelAssociator::SetPrefService(PrefServiceSyncable* pref_service) {
  DCHECK(pref_service_ == NULL);
  pref_service_ = pref_service;
}

void PrefModelAssociator::NotifySyncedPrefObservers(const std::string& path,
                                                    bool from_sync) const {
  SyncedPrefObserverMap::const_iterator observer_iter =
      synced_pref_observers_.find(path);
  if (observer_iter == synced_pref_observers_.end())
    return;
  SyncedPrefObserverList* observers = observer_iter->second;
  FOR_EACH_OBSERVER(SyncedPrefObserver, *observers,
                    OnSyncedPrefChanged(path, from_sync));
}