chrome/browser/supervised_user/supervised_user_sync_service.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "chrome/browser/supervised_user/supervised_user_sync_service.h"
   6
   7 #include <set>
   8
   9 #include "base/bind.h"
  10 #include "base/callback.h"
  11 #include "base/prefs/scoped_user_pref_update.h"
  12 #include "base/strings/string_number_conversions.h"
  13 #include "base/strings/stringprintf.h"
  14 #include "base/values.h"
  15 #include "chrome/browser/profiles/profile_avatar_icon_util.h"
  16 #include "chrome/common/pref_names.h"
  17 #include "components/pref_registry/pref_registry_syncable.h"
  18 #include "sync/api/sync_change.h"
  19 #include "sync/api/sync_data.h"
  20 #include "sync/api/sync_error.h"
  21 #include "sync/api/sync_error_factory.h"
  22 #include "sync/api/sync_merge_result.h"
  23 #include "sync/protocol/sync.pb.h"
  24
  25 #if defined(OS_CHROMEOS)
  26 #include "components/user_manager/user_image/default_user_images.h"
  27 #endif
  28
  29 using base::DictionaryValue;
  30 using user_prefs::PrefRegistrySyncable;
  31 using syncer::SUPERVISED_USERS;
  32 using syncer::ModelType;
  33 using syncer::SyncChange;
  34 using syncer::SyncChangeList;
  35 using syncer::SyncChangeProcessor;
  36 using syncer::SyncData;
  37 using syncer::SyncDataList;
  38 using syncer::SyncError;
  39 using syncer::SyncErrorFactory;
  40 using syncer::SyncMergeResult;
  41 using sync_pb::ManagedUserSpecifics;
  42
  43 namespace {
  44
  45 #if defined(OS_CHROMEOS)
  46 const char kChromeOSAvatarPrefix[] = "chromeos-avatar-index:";
  47 #else
  48 const char kChromeAvatarPrefix[] = "chrome-avatar-index:";
  49 #endif
  50
  51 SyncData CreateLocalSyncData(const std::string& id,
  52                              const std::string& name,
  53                              bool acknowledged,
  54                              const std::string& master_key,
  55                              const std::string& chrome_avatar,
  56                              const std::string& chromeos_avatar,
  57                              const std::string& password_signature_key,
  58                              const std::string& password_encryption_key) {
  59   ::sync_pb::EntitySpecifics specifics;
  60   specifics.mutable_managed_user()->set_id(id);
  61   specifics.mutable_managed_user()->set_name(name);
  62   if (!chrome_avatar.empty())
  63     specifics.mutable_managed_user()->set_chrome_avatar(chrome_avatar);
  64   if (!chromeos_avatar.empty())
  65     specifics.mutable_managed_user()->set_chromeos_avatar(chromeos_avatar);
  66   if (!master_key.empty())
  67     specifics.mutable_managed_user()->set_master_key(master_key);
  68   if (acknowledged)
  69     specifics.mutable_managed_user()->set_acknowledged(true);
  70   if (!password_signature_key.empty()) {
  71     specifics.mutable_managed_user()->
  72         set_password_signature_key(password_signature_key);
  73   }
  74   if (!password_encryption_key.empty()) {
  75     specifics.mutable_managed_user()->
  76         set_password_encryption_key(password_encryption_key);
  77   }
  78   return SyncData::CreateLocalData(id, name, specifics);
  79 }
  80
  81 SyncData CreateSyncDataFromDictionaryEntry(const std::string& id,
  82                                            const base::Value& value) {
  83   const base::DictionaryValue* dict = NULL;
  84   bool success = value.GetAsDictionary(&dict);
  85   DCHECK(success);
  86   bool acknowledged = false;
  87   dict->GetBoolean(SupervisedUserSyncService::kAcknowledged, &acknowledged);
  88   std::string name;
  89   dict->GetString(SupervisedUserSyncService::kName, &name);
  90   DCHECK(!name.empty());
  91   std::string master_key;
  92   dict->GetString(SupervisedUserSyncService::kMasterKey, &master_key);
  93   std::string chrome_avatar;
  94   dict->GetString(SupervisedUserSyncService::kChromeAvatar, &chrome_avatar);
  95   std::string chromeos_avatar;
  96   dict->GetString(SupervisedUserSyncService::kChromeOsAvatar, &chromeos_avatar);
  97   std::string signature;
  98   dict->GetString(SupervisedUserSyncService::kPasswordSignatureKey, &signature);
  99   std::string encryption;
 100   dict->GetString(SupervisedUserSyncService::kPasswordEncryptionKey,
 101                   &encryption);
 102
 103   return CreateLocalSyncData(id,
 104                              name,
 105                              acknowledged,
 106                              master_key,
 107                              chrome_avatar,
 108                              chromeos_avatar,
 109                              signature,
 110                              encryption);
 111 }
 112
 113 }  // namespace
 114
 115 const char SupervisedUserSyncService::kAcknowledged[] = "acknowledged";
 116 const char SupervisedUserSyncService::kChromeAvatar[] = "chromeAvatar";
 117 const char SupervisedUserSyncService::kChromeOsAvatar[] = "chromeOsAvatar";
 118 const char SupervisedUserSyncService::kMasterKey[] = "masterKey";
 119 const char SupervisedUserSyncService::kName[] = "name";
 120 const char SupervisedUserSyncService::kPasswordSignatureKey[] =
 121     "passwordSignatureKey";
 122 const char SupervisedUserSyncService::kPasswordEncryptionKey[] =
 123     "passwordEncryptionKey";
 124 const int SupervisedUserSyncService::kNoAvatar = -100;
 125
 126 SupervisedUserSyncService::SupervisedUserSyncService(PrefService* prefs)
 127     : prefs_(prefs) {
 128   pref_change_registrar_.Init(prefs_);
 129   pref_change_registrar_.Add(
 130       prefs::kGoogleServicesLastUsername,
 131       base::Bind(&SupervisedUserSyncService::OnLastSignedInUsernameChange,
 132                  base::Unretained(this)));
 133 }
 134
 135 SupervisedUserSyncService::~SupervisedUserSyncService() {
 136 }
 137
 138 // static
 139 void SupervisedUserSyncService::RegisterProfilePrefs(
 140     PrefRegistrySyncable* registry) {
 141   registry->RegisterDictionaryPref(prefs::kSupervisedUsers,
 142                                    PrefRegistrySyncable::UNSYNCABLE_PREF);
 143 }
 144
 145 // static
 146 bool SupervisedUserSyncService::GetAvatarIndex(const std::string& avatar_str,
 147                                                int* avatar_index) {
 148   DCHECK(avatar_index);
 149   if (avatar_str.empty()) {
 150     *avatar_index = kNoAvatar;
 151     return true;
 152   }
 153 #if defined(OS_CHROMEOS)
 154   const char* prefix = kChromeOSAvatarPrefix;
 155 #else
 156   const char* prefix = kChromeAvatarPrefix;
 157 #endif
 158   size_t prefix_len = strlen(prefix);
 159   if (avatar_str.size() <= prefix_len ||
 160       avatar_str.substr(0, prefix_len) != prefix) {
 161     return false;
 162   }
 163
 164   if (!base::StringToInt(avatar_str.substr(prefix_len), avatar_index))
 165     return false;
 166
 167   const int kChromeOSDummyAvatarIndex = -111;
 168
 169 #if defined(OS_CHROMEOS)
 170   return (*avatar_index == kChromeOSDummyAvatarIndex ||
 171           (*avatar_index >= user_manager::kFirstDefaultImageIndex &&
 172            *avatar_index < user_manager::kDefaultImagesCount));
 173 #else
 174   // Check if the Chrome avatar index is set to a dummy value. Some early
 175   // supervised user profiles on ChromeOS stored a dummy avatar index as a
 176   // Chrome Avatar before there was logic to sync the ChromeOS avatar
 177   // separately. Handle this as if the Chrome Avatar was not chosen yet (which
 178   // is correct for these profiles).
 179   if (*avatar_index == kChromeOSDummyAvatarIndex)
 180     *avatar_index = kNoAvatar;
 181   return (*avatar_index == kNoAvatar ||
 182           (*avatar_index >= 0 &&
 183            static_cast<size_t>(*avatar_index) <
 184                profiles::GetDefaultAvatarIconCount()));
 185 #endif
 186 }
 187
 188 // static
 189 std::string SupervisedUserSyncService::BuildAvatarString(int avatar_index) {
 190 #if defined(OS_CHROMEOS)
 191   const char* prefix = kChromeOSAvatarPrefix;
 192 #else
 193   const char* prefix = kChromeAvatarPrefix;
 194 #endif
 195   return base::StringPrintf("%s%d", prefix, avatar_index);
 196 }
 197
 198 void SupervisedUserSyncService::AddObserver(
 199     SupervisedUserSyncServiceObserver* observer) {
 200   observers_.AddObserver(observer);
 201 }
 202
 203 void SupervisedUserSyncService::RemoveObserver(
 204     SupervisedUserSyncServiceObserver* observer) {
 205   observers_.RemoveObserver(observer);
 206 }
 207
 208 scoped_ptr<base::DictionaryValue> SupervisedUserSyncService::CreateDictionary(
 209     const std::string& name,
 210     const std::string& master_key,
 211     const std::string& signature_key,
 212     const std::string& encryption_key,
 213     int avatar_index) {
 214   scoped_ptr<base::DictionaryValue> result(new base::DictionaryValue());
 215   result->SetString(kName, name);
 216   result->SetString(kMasterKey, master_key);
 217   result->SetString(kPasswordSignatureKey, signature_key);
 218   result->SetString(kPasswordEncryptionKey, encryption_key);
 219   // TODO(akuegel): Get rid of the avatar stuff here when Chrome OS switches
 220   // to the avatar index that is stored as a shared setting.
 221   std::string chrome_avatar;
 222   std::string chromeos_avatar;
 223 #if defined(OS_CHROMEOS)
 224   chromeos_avatar = BuildAvatarString(avatar_index);
 225 #else
 226   chrome_avatar = BuildAvatarString(avatar_index);
 227 #endif
 228   result->SetString(kChromeAvatar, chrome_avatar);
 229   result->SetString(kChromeOsAvatar, chromeos_avatar);
 230   return result.Pass();
 231 }
 232
 233 void SupervisedUserSyncService::AddSupervisedUser(
 234     const std::string& id,
 235     const std::string& name,
 236     const std::string& master_key,
 237     const std::string& signature_key,
 238     const std::string& encryption_key,
 239     int avatar_index) {
 240   UpdateSupervisedUserImpl(id,
 241                            name,
 242                            master_key,
 243                            signature_key,
 244                            encryption_key,
 245                            avatar_index,
 246                            true /* add */);
 247 }
 248
 249 void SupervisedUserSyncService::UpdateSupervisedUser(
 250     const std::string& id,
 251     const std::string& name,
 252     const std::string& master_key,
 253     const std::string& signature_key,
 254     const std::string& encryption_key,
 255     int avatar_index) {
 256   UpdateSupervisedUserImpl(id,
 257                            name,
 258                            master_key,
 259                            signature_key,
 260                            encryption_key,
 261                            avatar_index,
 262                            false /* update */);
 263 }
 264
 265 void SupervisedUserSyncService::UpdateSupervisedUserImpl(
 266     const std::string& id,
 267     const std::string& name,
 268     const std::string& master_key,
 269     const std::string& signature_key,
 270     const std::string& encryption_key,
 271     int avatar_index,
 272     bool add_user) {
 273   DictionaryPrefUpdate update(prefs_, prefs::kSupervisedUsers);
 274   base::DictionaryValue* dict = update.Get();
 275   scoped_ptr<base::DictionaryValue> value = CreateDictionary(
 276       name, master_key, signature_key, encryption_key, avatar_index);
 277
 278   DCHECK_EQ(add_user, !dict->HasKey(id));
 279   base::DictionaryValue* entry = value.get();
 280   dict->SetWithoutPathExpansion(id, value.release());
 281
 282   if (!sync_processor_)
 283     return;
 284
 285   // If we're already syncing, create a new change and upload it.
 286   SyncChangeList change_list;
 287   change_list.push_back(
 288       SyncChange(FROM_HERE,
 289                  add_user ? SyncChange::ACTION_ADD : SyncChange::ACTION_UPDATE,
 290                  CreateSyncDataFromDictionaryEntry(id, *entry)));
 291   SyncError error =
 292       sync_processor_->ProcessSyncChanges(FROM_HERE, change_list);
 293   DCHECK(!error.IsSet()) << error.ToString();
 294 }
 295
 296 void SupervisedUserSyncService::DeleteSupervisedUser(const std::string& id) {
 297   DictionaryPrefUpdate update(prefs_, prefs::kSupervisedUsers);
 298   bool success = update->RemoveWithoutPathExpansion(id, NULL);
 299   DCHECK(success);
 300
 301   if (!sync_processor_)
 302     return;
 303
 304   SyncChangeList change_list;
 305   change_list.push_back(SyncChange(
 306       FROM_HERE,
 307       SyncChange::ACTION_DELETE,
 308       SyncData::CreateLocalDelete(id, SUPERVISED_USERS)));
 309   SyncError sync_error =
 310       sync_processor_->ProcessSyncChanges(FROM_HERE, change_list);
 311   DCHECK(!sync_error.IsSet());
 312 }
 313
 314 const base::DictionaryValue* SupervisedUserSyncService::GetSupervisedUsers() {
 315   DCHECK(sync_processor_);
 316   return prefs_->GetDictionary(prefs::kSupervisedUsers);
 317 }
 318
 319 bool SupervisedUserSyncService::UpdateSupervisedUserAvatarIfNeeded(
 320     const std::string& id,
 321     int avatar_index) {
 322   DictionaryPrefUpdate update(prefs_, prefs::kSupervisedUsers);
 323   base::DictionaryValue* dict = update.Get();
 324   DCHECK(dict->HasKey(id));
 325   base::DictionaryValue* value = NULL;
 326   bool success = dict->GetDictionaryWithoutPathExpansion(id, &value);
 327   DCHECK(success);
 328
 329   bool acknowledged = false;
 330   value->GetBoolean(SupervisedUserSyncService::kAcknowledged, &acknowledged);
 331   std::string name;
 332   value->GetString(SupervisedUserSyncService::kName, &name);
 333   std::string master_key;
 334   value->GetString(SupervisedUserSyncService::kMasterKey, &master_key);
 335   std::string signature;
 336   value->GetString(SupervisedUserSyncService::kPasswordSignatureKey,
 337                    &signature);
 338   std::string encryption;
 339   value->GetString(SupervisedUserSyncService::kPasswordEncryptionKey,
 340                    &encryption);
 341   std::string chromeos_avatar;
 342   value->GetString(SupervisedUserSyncService::kChromeOsAvatar,
 343                    &chromeos_avatar);
 344   std::string chrome_avatar;
 345   value->GetString(SupervisedUserSyncService::kChromeAvatar, &chrome_avatar);
 346   // The following check is just for safety. We want to avoid that the existing
 347   // avatar selection is overwritten. Currently we don't allow the user to
 348   // choose a different avatar in the recreation dialog, anyway, if there is
 349   // already an avatar selected.
 350 #if defined(OS_CHROMEOS)
 351   if (!chromeos_avatar.empty() && avatar_index != kNoAvatar)
 352     return false;
 353 #else
 354   if (!chrome_avatar.empty() && avatar_index != kNoAvatar)
 355     return false;
 356 #endif
 357
 358   chrome_avatar = avatar_index == kNoAvatar ?
 359       std::string() : BuildAvatarString(avatar_index);
 360 #if defined(OS_CHROMEOS)
 361   value->SetString(kChromeOsAvatar, chrome_avatar);
 362 #else
 363   value->SetString(kChromeAvatar, chrome_avatar);
 364 #endif
 365
 366   if (!sync_processor_)
 367     return true;
 368
 369   SyncChangeList change_list;
 370   change_list.push_back(SyncChange(
 371       FROM_HERE,
 372       SyncChange::ACTION_UPDATE,
 373       CreateLocalSyncData(id, name, acknowledged, master_key,
 374                           chrome_avatar, chromeos_avatar,
 375                           signature, encryption)));
 376   SyncError error =
 377       sync_processor_->ProcessSyncChanges(FROM_HERE, change_list);
 378   DCHECK(!error.IsSet()) << error.ToString();
 379   return true;
 380 }
 381
 382 void SupervisedUserSyncService::ClearSupervisedUserAvatar(
 383     const std::string& id) {
 384   bool cleared = UpdateSupervisedUserAvatarIfNeeded(id, kNoAvatar);
 385   DCHECK(cleared);
 386 }
 387
 388 void SupervisedUserSyncService::GetSupervisedUsersAsync(
 389     const SupervisedUsersCallback& callback) {
 390   // If we are already syncing, just run the callback.
 391   if (sync_processor_) {
 392     callback.Run(GetSupervisedUsers());
 393     return;
 394   }
 395
 396   // Otherwise queue it up until we start syncing.
 397   callbacks_.push_back(callback);
 398 }
 399
 400 void SupervisedUserSyncService::Shutdown() {
 401   NotifySupervisedUsersSyncingStopped();
 402 }
 403
 404 SyncMergeResult SupervisedUserSyncService::MergeDataAndStartSyncing(
 405     ModelType type,
 406     const SyncDataList& initial_sync_data,
 407     scoped_ptr<SyncChangeProcessor> sync_processor,
 408     scoped_ptr<SyncErrorFactory> error_handler) {
 409   DCHECK_EQ(SUPERVISED_USERS, type);
 410   sync_processor_ = sync_processor.Pass();
 411   error_handler_ = error_handler.Pass();
 412
 413   SyncChangeList change_list;
 414   SyncMergeResult result(SUPERVISED_USERS);
 415
 416   DictionaryPrefUpdate update(prefs_, prefs::kSupervisedUsers);
 417   base::DictionaryValue* dict = update.Get();
 418   result.set_num_items_before_association(dict->size());
 419   std::set<std::string> seen_ids;
 420   int num_items_added = 0;
 421   int num_items_modified = 0;
 422   for (const SyncData& sync_data : initial_sync_data) {
 423     DCHECK_EQ(SUPERVISED_USERS, sync_data.GetDataType());
 424     const ManagedUserSpecifics& supervised_user =
 425         sync_data.GetSpecifics().managed_user();
 426     base::DictionaryValue* value = new base::DictionaryValue();
 427     value->SetString(kName, supervised_user.name());
 428     value->SetBoolean(kAcknowledged, supervised_user.acknowledged());
 429     value->SetString(kMasterKey, supervised_user.master_key());
 430     value->SetString(kChromeAvatar, supervised_user.chrome_avatar());
 431     value->SetString(kChromeOsAvatar, supervised_user.chromeos_avatar());
 432     value->SetString(kPasswordSignatureKey,
 433                      supervised_user.password_signature_key());
 434     value->SetString(kPasswordEncryptionKey,
 435                      supervised_user.password_encryption_key());
 436     if (dict->HasKey(supervised_user.id()))
 437       num_items_modified++;
 438     else
 439       num_items_added++;
 440     dict->SetWithoutPathExpansion(supervised_user.id(), value);
 441     seen_ids.insert(supervised_user.id());
 442   }
 443
 444   for (base::DictionaryValue::Iterator it(*dict); !it.IsAtEnd(); it.Advance()) {
 445     if (seen_ids.find(it.key()) != seen_ids.end())
 446       continue;
 447
 448     change_list.push_back(
 449         SyncChange(FROM_HERE,
 450                    SyncChange::ACTION_ADD,
 451                    CreateSyncDataFromDictionaryEntry(it.key(), it.value())));
 452   }
 453   result.set_error(sync_processor_->ProcessSyncChanges(FROM_HERE, change_list));
 454
 455   result.set_num_items_modified(num_items_modified);
 456   result.set_num_items_added(num_items_added);
 457   result.set_num_items_after_association(dict->size());
 458
 459   DispatchCallbacks();
 460
 461   return result;
 462 }
 463
 464 void SupervisedUserSyncService::StopSyncing(ModelType type) {
 465   DCHECK_EQ(SUPERVISED_USERS, type);
 466   // The observers may want to change the Sync data, so notify them before
 467   // resetting the |sync_processor_|.
 468   NotifySupervisedUsersSyncingStopped();
 469   sync_processor_.reset();
 470   error_handler_.reset();
 471 }
 472
 473 SyncDataList SupervisedUserSyncService::GetAllSyncData(
 474     ModelType type) const {
 475   SyncDataList data;
 476   DictionaryPrefUpdate update(prefs_, prefs::kSupervisedUsers);
 477   base::DictionaryValue* dict = update.Get();
 478   for (base::DictionaryValue::Iterator it(*dict); !it.IsAtEnd(); it.Advance())
 479     data.push_back(CreateSyncDataFromDictionaryEntry(it.key(), it.value()));
 480
 481   return data;
 482 }
 483
 484 SyncError SupervisedUserSyncService::ProcessSyncChanges(
 485     const tracked_objects::Location& from_here,
 486     const SyncChangeList& change_list) {
 487   SyncError error;
 488   DictionaryPrefUpdate update(prefs_, prefs::kSupervisedUsers);
 489   base::DictionaryValue* dict = update.Get();
 490   for (const SyncChange& sync_change : change_list) {
 491     SyncData data = sync_change.sync_data();
 492     DCHECK_EQ(SUPERVISED_USERS, data.GetDataType());
 493     const ManagedUserSpecifics& supervised_user =
 494         data.GetSpecifics().managed_user();
 495     switch (sync_change.change_type()) {
 496       case SyncChange::ACTION_ADD:
 497       case SyncChange::ACTION_UPDATE: {
 498         // Every item we get from the server should be acknowledged.
 499         DCHECK(supervised_user.acknowledged());
 500         const base::DictionaryValue* old_value = NULL;
 501         dict->GetDictionaryWithoutPathExpansion(supervised_user.id(),
 502                                                 &old_value);
 503
 504         // For an update action, the supervised user should already exist, for
 505         // an add action, it should not.
 506         DCHECK_EQ(
 507             old_value ? SyncChange::ACTION_UPDATE : SyncChange::ACTION_ADD,
 508             sync_change.change_type());
 509
 510         // If the supervised user switched from unacknowledged to acknowledged,
 511         // we might need to continue with a registration.
 512         if (old_value && !old_value->HasKey(kAcknowledged))
 513           NotifySupervisedUserAcknowledged(supervised_user.id());
 514
 515         base::DictionaryValue* value = new base::DictionaryValue;
 516         value->SetString(kName, supervised_user.name());
 517         value->SetBoolean(kAcknowledged, supervised_user.acknowledged());
 518         value->SetString(kMasterKey, supervised_user.master_key());
 519         value->SetString(kChromeAvatar, supervised_user.chrome_avatar());
 520         value->SetString(kChromeOsAvatar, supervised_user.chromeos_avatar());
 521         value->SetString(kPasswordSignatureKey,
 522                          supervised_user.password_signature_key());
 523         value->SetString(kPasswordEncryptionKey,
 524                          supervised_user.password_encryption_key());
 525         dict->SetWithoutPathExpansion(supervised_user.id(), value);
 526
 527         NotifySupervisedUsersChanged();
 528         break;
 529       }
 530       case SyncChange::ACTION_DELETE: {
 531         DCHECK(dict->HasKey(supervised_user.id())) << supervised_user.id();
 532         dict->RemoveWithoutPathExpansion(supervised_user.id(), NULL);
 533         break;
 534       }
 535       case SyncChange::ACTION_INVALID: {
 536         NOTREACHED();
 537         break;
 538       }
 539     }
 540   }
 541   return error;
 542 }
 543
 544 void SupervisedUserSyncService::OnLastSignedInUsernameChange() {
 545   DCHECK(!sync_processor_);
 546
 547   // If the last signed in user changes, we clear all data, to avoid supervised
 548   // users from one custodian appearing in another one's profile.
 549   prefs_->ClearPref(prefs::kSupervisedUsers);
 550 }
 551
 552 void SupervisedUserSyncService::NotifySupervisedUserAcknowledged(
 553     const std::string& supervised_user_id) {
 554   FOR_EACH_OBSERVER(SupervisedUserSyncServiceObserver, observers_,
 555                     OnSupervisedUserAcknowledged(supervised_user_id));
 556 }
 557
 558 void SupervisedUserSyncService::NotifySupervisedUsersSyncingStopped() {
 559   FOR_EACH_OBSERVER(SupervisedUserSyncServiceObserver, observers_,
 560                     OnSupervisedUsersSyncingStopped());
 561 }
 562
 563 void SupervisedUserSyncService::NotifySupervisedUsersChanged() {
 564   FOR_EACH_OBSERVER(SupervisedUserSyncServiceObserver,
 565                     observers_,
 566                     OnSupervisedUsersChanged());
 567 }
 568
 569 void SupervisedUserSyncService::DispatchCallbacks() {
 570   const base::DictionaryValue* supervised_users =
 571       prefs_->GetDictionary(prefs::kSupervisedUsers);
 572   for (const auto& callback : callbacks_)
 573     callback.Run(supervised_users);
 574   callbacks_.clear();
 575 }