chrome/browser/supervised_user/legacy/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/legacy/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.h"
  16 #include "chrome/browser/profiles/profile_avatar_icon_util.h"
  17 #include "chrome/browser/signin/signin_manager_factory.h"
  18 #include "chrome/common/pref_names.h"
  19 #include "components/pref_registry/pref_registry_syncable.h"
  20 #include "components/signin/core/browser/signin_manager.h"
  21 #include "sync/api/sync_change.h"
  22 #include "sync/api/sync_data.h"
  23 #include "sync/api/sync_error.h"
  24 #include "sync/api/sync_error_factory.h"
  25 #include "sync/api/sync_merge_result.h"
  26 #include "sync/protocol/sync.pb.h"
  27
  28 #if defined(OS_CHROMEOS)
  29 #include "components/user_manager/user_image/default_user_images.h"
  30 #endif
  31
  32 using base::DictionaryValue;
  33 using user_prefs::PrefRegistrySyncable;
  34 using syncer::SUPERVISED_USERS;
  35 using syncer::ModelType;
  36 using syncer::SyncChange;
  37 using syncer::SyncChangeList;
  38 using syncer::SyncChangeProcessor;
  39 using syncer::SyncData;
  40 using syncer::SyncDataList;
  41 using syncer::SyncError;
  42 using syncer::SyncErrorFactory;
  43 using syncer::SyncMergeResult;
  44 using sync_pb::ManagedUserSpecifics;
  45
  46 namespace {
  47
  48 #if defined(OS_CHROMEOS)
  49 const char kChromeOSAvatarPrefix[] = "chromeos-avatar-index:";
  50 #else
  51 const char kChromeAvatarPrefix[] = "chrome-avatar-index:";
  52 #endif
  53
  54 SyncData CreateLocalSyncData(const std::string& id,
  55                              const std::string& name,
  56                              bool acknowledged,
  57                              const std::string& master_key,
  58                              const std::string& chrome_avatar,
  59                              const std::string& chromeos_avatar,
  60                              const std::string& password_signature_key,
  61                              const std::string& password_encryption_key) {
  62   ::sync_pb::EntitySpecifics specifics;
  63   specifics.mutable_managed_user()->set_id(id);
  64   specifics.mutable_managed_user()->set_name(name);
  65   if (!chrome_avatar.empty())
  66     specifics.mutable_managed_user()->set_chrome_avatar(chrome_avatar);
  67   if (!chromeos_avatar.empty())
  68     specifics.mutable_managed_user()->set_chromeos_avatar(chromeos_avatar);
  69   if (!master_key.empty())
  70     specifics.mutable_managed_user()->set_master_key(master_key);
  71   if (acknowledged)
  72     specifics.mutable_managed_user()->set_acknowledged(true);
  73   if (!password_signature_key.empty()) {
  74     specifics.mutable_managed_user()->
  75         set_password_signature_key(password_signature_key);
  76   }
  77   if (!password_encryption_key.empty()) {
  78     specifics.mutable_managed_user()->
  79         set_password_encryption_key(password_encryption_key);
  80   }
  81   return SyncData::CreateLocalData(id, name, specifics);
  82 }
  83
  84 SyncData CreateSyncDataFromDictionaryEntry(const std::string& id,
  85                                            const base::Value& value) {
  86   const base::DictionaryValue* dict = NULL;
  87   bool success = value.GetAsDictionary(&dict);
  88   DCHECK(success);
  89   bool acknowledged = false;
  90   dict->GetBoolean(SupervisedUserSyncService::kAcknowledged, &acknowledged);
  91   std::string name;
  92   dict->GetString(SupervisedUserSyncService::kName, &name);
  93   DCHECK(!name.empty());
  94   std::string master_key;
  95   dict->GetString(SupervisedUserSyncService::kMasterKey, &master_key);
  96   std::string chrome_avatar;
  97   dict->GetString(SupervisedUserSyncService::kChromeAvatar, &chrome_avatar);
  98   std::string chromeos_avatar;
  99   dict->GetString(SupervisedUserSyncService::kChromeOsAvatar, &chromeos_avatar);
 100   std::string signature;
 101   dict->GetString(SupervisedUserSyncService::kPasswordSignatureKey, &signature);
 102   std::string encryption;
 103   dict->GetString(SupervisedUserSyncService::kPasswordEncryptionKey,
 104                   &encryption);
 105
 106   return CreateLocalSyncData(id,
 107                              name,
 108                              acknowledged,
 109                              master_key,
 110                              chrome_avatar,
 111                              chromeos_avatar,
 112                              signature,
 113                              encryption);
 114 }
 115
 116 }  // namespace
 117
 118 const char SupervisedUserSyncService::kAcknowledged[] = "acknowledged";
 119 const char SupervisedUserSyncService::kChromeAvatar[] = "chromeAvatar";
 120 const char SupervisedUserSyncService::kChromeOsAvatar[] = "chromeOsAvatar";
 121 const char SupervisedUserSyncService::kMasterKey[] = "masterKey";
 122 const char SupervisedUserSyncService::kName[] = "name";
 123 const char SupervisedUserSyncService::kPasswordSignatureKey[] =
 124     "passwordSignatureKey";
 125 const char SupervisedUserSyncService::kPasswordEncryptionKey[] =
 126     "passwordEncryptionKey";
 127 const int SupervisedUserSyncService::kNoAvatar = -100;
 128
 129 SupervisedUserSyncService::SupervisedUserSyncService(Profile* profile)
 130     : profile_(profile), prefs_(profile->GetPrefs()) {
 131   SigninManagerFactory::GetForProfile(profile_)->AddObserver(this);
 132 }
 133
 134 SupervisedUserSyncService::~SupervisedUserSyncService() {
 135 }
 136
 137 // static
 138 void SupervisedUserSyncService::RegisterProfilePrefs(
 139     PrefRegistrySyncable* registry) {
 140   registry->RegisterDictionaryPref(prefs::kSupervisedUsers);
 141 }
 142
 143 // static
 144 bool SupervisedUserSyncService::GetAvatarIndex(const std::string& avatar_str,
 145                                                int* avatar_index) {
 146   DCHECK(avatar_index);
 147   if (avatar_str.empty()) {
 148     *avatar_index = kNoAvatar;
 149     return true;
 150   }
 151 #if defined(OS_CHROMEOS)
 152   const char* prefix = kChromeOSAvatarPrefix;
 153 #else
 154   const char* prefix = kChromeAvatarPrefix;
 155 #endif
 156   size_t prefix_len = strlen(prefix);
 157   if (avatar_str.size() <= prefix_len ||
 158       avatar_str.substr(0, prefix_len) != prefix) {
 159     return false;
 160   }
 161
 162   if (!base::StringToInt(avatar_str.substr(prefix_len), avatar_index))
 163     return false;
 164
 165   const int kChromeOSDummyAvatarIndex = -111;
 166
 167 #if defined(OS_CHROMEOS)
 168   return (*avatar_index == kChromeOSDummyAvatarIndex ||
 169           (*avatar_index >= user_manager::kFirstDefaultImageIndex &&
 170            *avatar_index < user_manager::kDefaultImagesCount));
 171 #else
 172   // Check if the Chrome avatar index is set to a dummy value. Some early
 173   // supervised user profiles on ChromeOS stored a dummy avatar index as a
 174   // Chrome Avatar before there was logic to sync the ChromeOS avatar
 175   // separately. Handle this as if the Chrome Avatar was not chosen yet (which
 176   // is correct for these profiles).
 177   if (*avatar_index == kChromeOSDummyAvatarIndex)
 178     *avatar_index = kNoAvatar;
 179   return (*avatar_index == kNoAvatar ||
 180           (*avatar_index >= 0 &&
 181            static_cast<size_t>(*avatar_index) <
 182                profiles::GetDefaultAvatarIconCount()));
 183 #endif
 184 }
 185
 186 // static
 187 std::string SupervisedUserSyncService::BuildAvatarString(int avatar_index) {
 188 #if defined(OS_CHROMEOS)
 189   const char* prefix = kChromeOSAvatarPrefix;
 190 #else
 191   const char* prefix = kChromeAvatarPrefix;
 192 #endif
 193   return base::StringPrintf("%s%d", prefix, avatar_index);
 194 }
 195
 196 void SupervisedUserSyncService::AddObserver(
 197     SupervisedUserSyncServiceObserver* observer) {
 198   observers_.AddObserver(observer);
 199 }
 200
 201 void SupervisedUserSyncService::RemoveObserver(
 202     SupervisedUserSyncServiceObserver* observer) {
 203   observers_.RemoveObserver(observer);
 204 }
 205
 206 scoped_ptr<base::DictionaryValue> SupervisedUserSyncService::CreateDictionary(
 207     const std::string& name,
 208     const std::string& master_key,
 209     const std::string& signature_key,
 210     const std::string& encryption_key,
 211     int avatar_index) {
 212   scoped_ptr<base::DictionaryValue> result(new base::DictionaryValue());
 213   result->SetString(kName, name);
 214   result->SetString(kMasterKey, master_key);
 215   result->SetString(kPasswordSignatureKey, signature_key);
 216   result->SetString(kPasswordEncryptionKey, encryption_key);
 217   // TODO(akuegel): Get rid of the avatar stuff here when Chrome OS switches
 218   // to the avatar index that is stored as a shared setting.
 219   std::string chrome_avatar;
 220   std::string chromeos_avatar;
 221 #if defined(OS_CHROMEOS)
 222   chromeos_avatar = BuildAvatarString(avatar_index);
 223 #else
 224   chrome_avatar = BuildAvatarString(avatar_index);
 225 #endif
 226   result->SetString(kChromeAvatar, chrome_avatar);
 227   result->SetString(kChromeOsAvatar, chromeos_avatar);
 228   return result.Pass();
 229 }
 230
 231 void SupervisedUserSyncService::AddSupervisedUser(
 232     const std::string& id,
 233     const std::string& name,
 234     const std::string& master_key,
 235     const std::string& signature_key,
 236     const std::string& encryption_key,
 237     int avatar_index) {
 238   UpdateSupervisedUserImpl(id,
 239                            name,
 240                            master_key,
 241                            signature_key,
 242                            encryption_key,
 243                            avatar_index,
 244                            true /* add */);
 245 }
 246
 247 void SupervisedUserSyncService::UpdateSupervisedUser(
 248     const std::string& id,
 249     const std::string& name,
 250     const std::string& master_key,
 251     const std::string& signature_key,
 252     const std::string& encryption_key,
 253     int avatar_index) {
 254   UpdateSupervisedUserImpl(id,
 255                            name,
 256                            master_key,
 257                            signature_key,
 258                            encryption_key,
 259                            avatar_index,
 260                            false /* update */);
 261 }
 262
 263 void SupervisedUserSyncService::UpdateSupervisedUserImpl(
 264     const std::string& id,
 265     const std::string& name,
 266     const std::string& master_key,
 267     const std::string& signature_key,
 268     const std::string& encryption_key,
 269     int avatar_index,
 270     bool add_user) {
 271   DictionaryPrefUpdate update(prefs_, prefs::kSupervisedUsers);
 272   base::DictionaryValue* dict = update.Get();
 273   scoped_ptr<base::DictionaryValue> value = CreateDictionary(
 274       name, master_key, signature_key, encryption_key, avatar_index);
 275
 276   DCHECK_EQ(add_user, !dict->HasKey(id));
 277   base::DictionaryValue* entry = value.get();
 278   dict->SetWithoutPathExpansion(id, value.release());
 279
 280   if (!sync_processor_)
 281     return;
 282
 283   // If we're already syncing, create a new change and upload it.
 284   SyncChangeList change_list;
 285   change_list.push_back(
 286       SyncChange(FROM_HERE,
 287                  add_user ? SyncChange::ACTION_ADD : SyncChange::ACTION_UPDATE,
 288                  CreateSyncDataFromDictionaryEntry(id, *entry)));
 289   SyncError error =
 290       sync_processor_->ProcessSyncChanges(FROM_HERE, change_list);
 291   DCHECK(!error.IsSet()) << error.ToString();
 292 }
 293
 294 void SupervisedUserSyncService::DeleteSupervisedUser(const std::string& id) {
 295   DictionaryPrefUpdate update(prefs_, prefs::kSupervisedUsers);
 296   bool success = update->RemoveWithoutPathExpansion(id, NULL);
 297   DCHECK(success);
 298
 299   if (!sync_processor_)
 300     return;
 301
 302   SyncChangeList change_list;
 303   change_list.push_back(SyncChange(
 304       FROM_HERE,
 305       SyncChange::ACTION_DELETE,
 306       SyncData::CreateLocalDelete(id, SUPERVISED_USERS)));
 307   SyncError sync_error =
 308       sync_processor_->ProcessSyncChanges(FROM_HERE, change_list);
 309   DCHECK(!sync_error.IsSet());
 310 }
 311
 312 const base::DictionaryValue* SupervisedUserSyncService::GetSupervisedUsers() {
 313   DCHECK(sync_processor_);
 314   return prefs_->GetDictionary(prefs::kSupervisedUsers);
 315 }
 316
 317 bool SupervisedUserSyncService::UpdateSupervisedUserAvatarIfNeeded(
 318     const std::string& id,
 319     int avatar_index) {
 320   DictionaryPrefUpdate update(prefs_, prefs::kSupervisedUsers);
 321   base::DictionaryValue* dict = update.Get();
 322   DCHECK(dict->HasKey(id));
 323   base::DictionaryValue* value = NULL;
 324   bool success = dict->GetDictionaryWithoutPathExpansion(id, &value);
 325   DCHECK(success);
 326
 327   bool acknowledged = false;
 328   value->GetBoolean(SupervisedUserSyncService::kAcknowledged, &acknowledged);
 329   std::string name;
 330   value->GetString(SupervisedUserSyncService::kName, &name);
 331   std::string master_key;
 332   value->GetString(SupervisedUserSyncService::kMasterKey, &master_key);
 333   std::string signature;
 334   value->GetString(SupervisedUserSyncService::kPasswordSignatureKey,
 335                    &signature);
 336   std::string encryption;
 337   value->GetString(SupervisedUserSyncService::kPasswordEncryptionKey,
 338                    &encryption);
 339   std::string chromeos_avatar;
 340   value->GetString(SupervisedUserSyncService::kChromeOsAvatar,
 341                    &chromeos_avatar);
 342   std::string chrome_avatar;
 343   value->GetString(SupervisedUserSyncService::kChromeAvatar, &chrome_avatar);
 344   // The following check is just for safety. We want to avoid that the existing
 345   // avatar selection is overwritten. Currently we don't allow the user to
 346   // choose a different avatar in the recreation dialog, anyway, if there is
 347   // already an avatar selected.
 348 #if defined(OS_CHROMEOS)
 349   if (!chromeos_avatar.empty() && avatar_index != kNoAvatar)
 350     return false;
 351 #else
 352   if (!chrome_avatar.empty() && avatar_index != kNoAvatar)
 353     return false;
 354 #endif
 355
 356   chrome_avatar = avatar_index == kNoAvatar ?
 357       std::string() : BuildAvatarString(avatar_index);
 358 #if defined(OS_CHROMEOS)
 359   value->SetString(kChromeOsAvatar, chrome_avatar);
 360 #else
 361   value->SetString(kChromeAvatar, chrome_avatar);
 362 #endif
 363
 364   if (!sync_processor_)
 365     return true;
 366
 367   SyncChangeList change_list;
 368   change_list.push_back(SyncChange(
 369       FROM_HERE,
 370       SyncChange::ACTION_UPDATE,
 371       CreateLocalSyncData(id, name, acknowledged, master_key,
 372                           chrome_avatar, chromeos_avatar,
 373                           signature, encryption)));
 374   SyncError error =
 375       sync_processor_->ProcessSyncChanges(FROM_HERE, change_list);
 376   DCHECK(!error.IsSet()) << error.ToString();
 377   return true;
 378 }
 379
 380 void SupervisedUserSyncService::ClearSupervisedUserAvatar(
 381     const std::string& id) {
 382   bool cleared = UpdateSupervisedUserAvatarIfNeeded(id, kNoAvatar);
 383   DCHECK(cleared);
 384 }
 385
 386 void SupervisedUserSyncService::GetSupervisedUsersAsync(
 387     const SupervisedUsersCallback& callback) {
 388   // If we are already syncing, just run the callback.
 389   if (sync_processor_) {
 390     callback.Run(GetSupervisedUsers());
 391     return;
 392   }
 393
 394   // Otherwise queue it up until we start syncing.
 395   callbacks_.push_back(callback);
 396 }
 397
 398 void SupervisedUserSyncService::Shutdown() {
 399   NotifySupervisedUsersSyncingStopped();
 400   SigninManagerFactory::GetForProfile(profile_)->RemoveObserver(this);
 401 }
 402
 403 SyncMergeResult SupervisedUserSyncService::MergeDataAndStartSyncing(
 404     ModelType type,
 405     const SyncDataList& initial_sync_data,
 406     scoped_ptr<SyncChangeProcessor> sync_processor,
 407     scoped_ptr<SyncErrorFactory> error_handler) {
 408   DCHECK_EQ(SUPERVISED_USERS, type);
 409   sync_processor_ = sync_processor.Pass();
 410   error_handler_ = error_handler.Pass();
 411
 412   SyncChangeList change_list;
 413   SyncMergeResult result(SUPERVISED_USERS);
 414
 415   DictionaryPrefUpdate update(prefs_, prefs::kSupervisedUsers);
 416   base::DictionaryValue* dict = update.Get();
 417   result.set_num_items_before_association(dict->size());
 418   std::set<std::string> seen_ids;
 419   int num_items_added = 0;
 420   int num_items_modified = 0;
 421   for (const SyncData& sync_data : initial_sync_data) {
 422     DCHECK_EQ(SUPERVISED_USERS, sync_data.GetDataType());
 423     const ManagedUserSpecifics& supervised_user =
 424         sync_data.GetSpecifics().managed_user();
 425     base::DictionaryValue* value = new base::DictionaryValue();
 426     value->SetString(kName, supervised_user.name());
 427     value->SetBoolean(kAcknowledged, supervised_user.acknowledged());
 428     value->SetString(kMasterKey, supervised_user.master_key());
 429     value->SetString(kChromeAvatar, supervised_user.chrome_avatar());
 430     value->SetString(kChromeOsAvatar, supervised_user.chromeos_avatar());
 431     value->SetString(kPasswordSignatureKey,
 432                      supervised_user.password_signature_key());
 433     value->SetString(kPasswordEncryptionKey,
 434                      supervised_user.password_encryption_key());
 435     if (dict->HasKey(supervised_user.id()))
 436       num_items_modified++;
 437     else
 438       num_items_added++;
 439     dict->SetWithoutPathExpansion(supervised_user.id(), value);
 440     seen_ids.insert(supervised_user.id());
 441   }
 442
 443   for (base::DictionaryValue::Iterator it(*dict); !it.IsAtEnd(); it.Advance()) {
 444     if (seen_ids.find(it.key()) != seen_ids.end())
 445       continue;
 446
 447     change_list.push_back(
 448         SyncChange(FROM_HERE,
 449                    SyncChange::ACTION_ADD,
 450                    CreateSyncDataFromDictionaryEntry(it.key(), it.value())));
 451   }
 452   result.set_error(sync_processor_->ProcessSyncChanges(FROM_HERE, change_list));
 453
 454   result.set_num_items_modified(num_items_modified);
 455   result.set_num_items_added(num_items_added);
 456   result.set_num_items_after_association(dict->size());
 457
 458   DispatchCallbacks();
 459
 460   return result;
 461 }
 462
 463 void SupervisedUserSyncService::StopSyncing(ModelType type) {
 464   DCHECK_EQ(SUPERVISED_USERS, type);
 465   // The observers may want to change the Sync data, so notify them before
 466   // resetting the |sync_processor_|.
 467   NotifySupervisedUsersSyncingStopped();
 468   sync_processor_.reset();
 469   error_handler_.reset();
 470 }
 471
 472 SyncDataList SupervisedUserSyncService::GetAllSyncData(
 473     ModelType type) const {
 474   SyncDataList data;
 475   DictionaryPrefUpdate update(prefs_, prefs::kSupervisedUsers);
 476   base::DictionaryValue* dict = update.Get();
 477   for (base::DictionaryValue::Iterator it(*dict); !it.IsAtEnd(); it.Advance())
 478     data.push_back(CreateSyncDataFromDictionaryEntry(it.key(), it.value()));
 479
 480   return data;
 481 }
 482
 483 SyncError SupervisedUserSyncService::ProcessSyncChanges(
 484     const tracked_objects::Location& from_here,
 485     const SyncChangeList& change_list) {
 486   SyncError error;
 487   DictionaryPrefUpdate update(prefs_, prefs::kSupervisedUsers);
 488   base::DictionaryValue* dict = update.Get();
 489   for (const SyncChange& sync_change : change_list) {
 490     SyncData data = sync_change.sync_data();
 491     DCHECK_EQ(SUPERVISED_USERS, data.GetDataType());
 492     const ManagedUserSpecifics& supervised_user =
 493         data.GetSpecifics().managed_user();
 494     switch (sync_change.change_type()) {
 495       case SyncChange::ACTION_ADD:
 496       case SyncChange::ACTION_UPDATE: {
 497         // Every item we get from the server should be acknowledged.
 498         DCHECK(supervised_user.acknowledged());
 499         const base::DictionaryValue* old_value = NULL;
 500         dict->GetDictionaryWithoutPathExpansion(supervised_user.id(),
 501                                                 &old_value);
 502
 503         // For an update action, the supervised user should already exist, for
 504         // an add action, it should not.
 505         DCHECK_EQ(
 506             old_value ? SyncChange::ACTION_UPDATE : SyncChange::ACTION_ADD,
 507             sync_change.change_type());
 508
 509         // If the supervised user switched from unacknowledged to acknowledged,
 510         // we might need to continue with a registration.
 511         if (old_value && !old_value->HasKey(kAcknowledged))
 512           NotifySupervisedUserAcknowledged(supervised_user.id());
 513
 514         base::DictionaryValue* value = new base::DictionaryValue;
 515         value->SetString(kName, supervised_user.name());
 516         value->SetBoolean(kAcknowledged, supervised_user.acknowledged());
 517         value->SetString(kMasterKey, supervised_user.master_key());
 518         value->SetString(kChromeAvatar, supervised_user.chrome_avatar());
 519         value->SetString(kChromeOsAvatar, supervised_user.chromeos_avatar());
 520         value->SetString(kPasswordSignatureKey,
 521                          supervised_user.password_signature_key());
 522         value->SetString(kPasswordEncryptionKey,
 523                          supervised_user.password_encryption_key());
 524         dict->SetWithoutPathExpansion(supervised_user.id(), value);
 525
 526         NotifySupervisedUsersChanged();
 527         break;
 528       }
 529       case SyncChange::ACTION_DELETE: {
 530         DCHECK(dict->HasKey(supervised_user.id())) << supervised_user.id();
 531         dict->RemoveWithoutPathExpansion(supervised_user.id(), NULL);
 532         break;
 533       }
 534       case SyncChange::ACTION_INVALID: {
 535         NOTREACHED();
 536         break;
 537       }
 538     }
 539   }
 540   return error;
 541 }
 542
 543 void SupervisedUserSyncService::GoogleSignedOut(
 544     const std::string& account_id,
 545     const std::string& username) {
 546   DCHECK(!sync_processor_);
 547
 548   // Clear all data on signout, to avoid supervised users from one custodian
 549   // appearing in another one's profile.
 550   prefs_->ClearPref(prefs::kSupervisedUsers);
 551 }
 552
 553 void SupervisedUserSyncService::NotifySupervisedUserAcknowledged(
 554     const std::string& supervised_user_id) {
 555   FOR_EACH_OBSERVER(SupervisedUserSyncServiceObserver, observers_,
 556                     OnSupervisedUserAcknowledged(supervised_user_id));
 557 }
 558
 559 void SupervisedUserSyncService::NotifySupervisedUsersSyncingStopped() {
 560   FOR_EACH_OBSERVER(SupervisedUserSyncServiceObserver, observers_,
 561                     OnSupervisedUsersSyncingStopped());
 562 }
 563
 564 void SupervisedUserSyncService::NotifySupervisedUsersChanged() {
 565   FOR_EACH_OBSERVER(SupervisedUserSyncServiceObserver,
 566                     observers_,
 567                     OnSupervisedUsersChanged());
 568 }
 569
 570 void SupervisedUserSyncService::DispatchCallbacks() {
 571   const base::DictionaryValue* supervised_users =
 572       prefs_->GetDictionary(prefs::kSupervisedUsers);
 573   for (const auto& callback : callbacks_)
 574     callback.Run(supervised_users);
 575   callbacks_.clear();
 576 }