Revert of [sync] Replace FakeServer's implementation with LoopbackServer invocations.

components/sync/test/fake_server/fake_server.cc

Index: components/sync/test/fake_server/fake_server.cc
diff --git a/components/sync/test/fake_server/fake_server.cc b/components/sync/test/fake_server/fake_server.cc
index c3462b1abc2a581b2b52895c7617f05797e2e3c0..de1cb209907ecd8ea7256b7e968a9d785c977fc4 100644
--- a/components/sync/test/fake_server/fake_server.cc
+++ b/components/sync/test/fake_server/fake_server.cc
@@ -17,8 +17,10 @@
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/synchronization/lock.h"
-#include "base/threading/thread_restrictions.h"
-#include "components/sync/engine_impl/net/server_connection_manager.h"
+#include "components/sync/test/fake_server/bookmark_entity.h"
+#include "components/sync/test/fake_server/permanent_entity.h"
+#include "components/sync/test/fake_server/tombstone_entity.h"
+#include "components/sync/test/fake_server/unique_client_entity.h"
 #include "net/base/net_errors.h"
 #include "net/http/http_status_code.h"
 
@@ -26,28 +28,188 @@
 using std::vector;
 using syncer::GetModelType;
 using syncer::GetModelTypeFromSpecifics;
-using syncer::LoopbackServerEntity;
 using syncer::ModelType;
 using syncer::ModelTypeSet;
 
 namespace fake_server {
 
+class FakeServerEntity;
+
+namespace {
+
+// The default keystore key.
+static const char kDefaultKeystoreKey[] = "1111111111111111";
+
+// Properties of the bookmark bar permanent folder.
+static const char kBookmarkBarFolderServerTag[] = "bookmark_bar";
+static const char kBookmarkBarFolderName[] = "Bookmark Bar";
+
+// Properties of the other bookmarks permanent folder.
+static const char kOtherBookmarksFolderServerTag[] = "other_bookmarks";
+static const char kOtherBookmarksFolderName[] = "Other Bookmarks";
+
+// Properties of the synced bookmarks permanent folder.
+static const char kSyncedBookmarksFolderServerTag[] = "synced_bookmarks";
+static const char kSyncedBookmarksFolderName[] = "Synced Bookmarks";
+
+// A filter used during GetUpdates calls to determine what information to
+// send back to the client; filtering out old entities and tracking versions to
+// use in response progress markers. Note that only the GetUpdatesMessage's
+// from_progress_marker is used to determine this; legacy fields are ignored.
+class UpdateSieve {
+ public:
+  explicit UpdateSieve(const sync_pb::GetUpdatesMessage& message)
+      : UpdateSieve(MessageToVersionMap(message)) {}
+  ~UpdateSieve() {}
+
+  // Sets the progress markers in |get_updates_response| based on the highest
+  // version between request progress markers and response entities.
+  void SetProgressMarkers(
+      sync_pb::GetUpdatesResponse* get_updates_response) const {
+    for (const auto& kv : response_version_map_) {
+      sync_pb::DataTypeProgressMarker* new_marker =
+          get_updates_response->add_new_progress_marker();
+      new_marker->set_data_type_id(
+          GetSpecificsFieldNumberFromModelType(kv.first));
+      new_marker->set_token(base::Int64ToString(kv.second));
+    }
+  }
+
+  // Determines whether the server should send an |entity| to the client as
+  // part of a GetUpdatesResponse. Update internal tracking of max versions as a
+  // side effect which will later be used to set response progress markers.
+  bool ClientWantsItem(const FakeServerEntity& entity) {
+    int64_t version = entity.GetVersion();
+    ModelType type = entity.model_type();
+    response_version_map_[type] =
+        std::max(response_version_map_[type], version);
+    auto it = request_version_map_.find(type);
+    return it == request_version_map_.end() ? false : it->second < version;
+  }
+
+ private:
+  using ModelTypeToVersionMap = std::map<ModelType, int64_t>;
+
+  static UpdateSieve::ModelTypeToVersionMap MessageToVersionMap(
+      const sync_pb::GetUpdatesMessage& get_updates_message) {
+    CHECK_GT(get_updates_message.from_progress_marker_size(), 0)
+        << "A GetUpdates request must have at least one progress marker.";
+    ModelTypeToVersionMap request_version_map;
+
+    for (int i = 0; i < get_updates_message.from_progress_marker_size(); i++) {
+      sync_pb::DataTypeProgressMarker marker =
+          get_updates_message.from_progress_marker(i);
+
+      int64_t version = 0;
+      // Let the version remain zero if there is no token or an empty token (the
+      // first request for this type).
+      if (marker.has_token() && !marker.token().empty()) {
+        bool parsed = base::StringToInt64(marker.token(), &version);
+        CHECK(parsed) << "Unable to parse progress marker token.";
+      }
+
+      ModelType model_type =
+          syncer::GetModelTypeFromSpecificsFieldNumber(marker.data_type_id());
+      DCHECK(request_version_map.find(model_type) == request_version_map.end());
+      request_version_map[model_type] = version;
+    }
+    return request_version_map;
+  }
+
+  explicit UpdateSieve(const ModelTypeToVersionMap request_version_map)
+      : request_version_map_(request_version_map),
+        response_version_map_(request_version_map) {}
+
+  // The largest versions the client has seen before this request, and is used
+  // to filter entities to send back to clients. The values in this map are not
+  // updated after being initially set. The presence of a type in this map is a
+  // proxy for the desire to receive results about this type.
+  const ModelTypeToVersionMap request_version_map_;
+
+  // The largest versions seen between client and server, ultimately used to
+  // send progress markers back to the client.
+  ModelTypeToVersionMap response_version_map_;
+};
+
+// Returns whether |entity| is deleted or permanent.
+bool IsDeletedOrPermanent(const FakeServerEntity& entity) {
+  return entity.IsDeleted() || entity.IsPermanent();
+}
+
+}  // namespace
+
 FakeServer::FakeServer()
-    : authenticated_(true),
+    : version_(0),
+      store_birthday_(0),
+      authenticated_(true),
       error_type_(sync_pb::SyncEnums::SUCCESS),
       alternate_triggered_errors_(false),
       request_counter_(0),
       network_enabled_(true),
       weak_ptr_factory_(this) {
-  loopback_server_storage_ = base::MakeUnique<base::ScopedTempDir>();
-  base::ThreadRestrictions::SetIOAllowed(true);
-  DCHECK(loopback_server_storage_->CreateUniqueTempDir());
-  loopback_server_ = base::MakeUnique<syncer::LoopbackServer>(
-      loopback_server_storage_->GetPath().AppendASCII("profile.pb"));
-  loopback_server_->set_observer_for_tests(this);
+  Init();
 }
 
 FakeServer::~FakeServer() {}
+
+void FakeServer::Init() {
+  keystore_keys_.push_back(kDefaultKeystoreKey);
+
+  const bool create_result = CreateDefaultPermanentItems();
+  DCHECK(create_result) << "Permanent items were not created successfully.";
+}
+
+bool FakeServer::CreatePermanentBookmarkFolder(const std::string& server_tag,
+                                               const std::string& name) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  std::unique_ptr<FakeServerEntity> entity =
+      PermanentEntity::Create(syncer::BOOKMARKS, server_tag, name,
+                              ModelTypeToRootTag(syncer::BOOKMARKS));
+  if (!entity)
+    return false;
+
+  SaveEntity(std::move(entity));
+  return true;
+}
+
+bool FakeServer::CreateDefaultPermanentItems() {
+  // Permanent folders are always required for Bookmarks (hierarchical
+  // structure) and Nigori (data stored in permanent root folder).
+  ModelTypeSet permanent_folder_types =
+      ModelTypeSet(syncer::BOOKMARKS, syncer::NIGORI);
+
+  for (ModelTypeSet::Iterator it = permanent_folder_types.First(); it.Good();
+       it.Inc()) {
+    ModelType model_type = it.Get();
+
+    std::unique_ptr<FakeServerEntity> top_level_entity =
+        PermanentEntity::CreateTopLevel(model_type);
+    if (!top_level_entity) {
+      return false;
+    }
+    SaveEntity(std::move(top_level_entity));
+
+    if (model_type == syncer::BOOKMARKS) {
+      if (!CreatePermanentBookmarkFolder(kBookmarkBarFolderServerTag,
+                                         kBookmarkBarFolderName))
+        return false;
+      if (!CreatePermanentBookmarkFolder(kOtherBookmarksFolderServerTag,
+                                         kOtherBookmarksFolderName))
+        return false;
+    }
+  }
+
+  return true;
+}
+
+void FakeServer::UpdateEntityVersion(FakeServerEntity* entity) {
+  entity->SetVersion(++version_);
+}
+
+void FakeServer::SaveEntity(std::unique_ptr<FakeServerEntity> entity) {
+  UpdateEntityVersion(entity.get());
+  entities_[entity->id()] = std::move(entity);
+}
 
 void FakeServer::HandleCommand(const string& request,
                                const base::Closure& completion_closure,
@@ -55,7 +217,6 @@
                                int* response_code,
                                std::string* response) {
   DCHECK(thread_checker_.CalledOnValidThread());
-
   if (!network_enabled_) {
     *error_code = net::ERR_FAILED;
     *response_code = net::ERR_FAILED;
@@ -73,43 +234,66 @@
     return;
   }
 
+  sync_pb::ClientToServerMessage message;
+  bool parsed = message.ParseFromString(request);
+  CHECK(parsed) << "Unable to parse the ClientToServerMessage.";
+
   sync_pb::ClientToServerResponse response_proto;
-  *response_code = 200;
-  *error_code = 0;
-  if (error_type_ != sync_pb::SyncEnums::SUCCESS &&
-      ShouldSendTriggeredError()) {
+
+  if (message.has_store_birthday() &&
+      message.store_birthday() != GetStoreBirthday()) {
+    response_proto.set_error_code(sync_pb::SyncEnums::NOT_MY_BIRTHDAY);
+  } else if (error_type_ != sync_pb::SyncEnums::SUCCESS &&
+             ShouldSendTriggeredError()) {
     response_proto.set_error_code(error_type_);
   } else if (triggered_actionable_error_.get() && ShouldSendTriggeredError()) {
     sync_pb::ClientToServerResponse_Error* error =
         response_proto.mutable_error();
     error->CopyFrom(*(triggered_actionable_error_.get()));
   } else {
-    sync_pb::ClientToServerMessage message;
-    bool parsed = message.ParseFromString(request);
-    CHECK(parsed) << "Unable to parse the ClientToServerMessage.";
+    bool success = false;
     switch (message.message_contents()) {
       case sync_pb::ClientToServerMessage::GET_UPDATES:
         last_getupdates_message_ = message;
+        success = HandleGetUpdatesRequest(message.get_updates(),
+                                          response_proto.mutable_get_updates());
         break;
       case sync_pb::ClientToServerMessage::COMMIT:
         last_commit_message_ = message;
+        success = HandleCommitRequest(message.commit(),
+                                      message.invalidator_client_id(),
+                                      response_proto.mutable_commit());
+        break;
+      case sync_pb::ClientToServerMessage::CLEAR_SERVER_DATA:
+        ClearServerData();
+        response_proto.mutable_clear_server_data();
+        success = true;
         break;
       default:
-        break;
-        // Don't care.
-    }
-
-    int64_t response_code_large;
-    syncer::HttpResponse::ServerConnectionCode server_status;
-    base::ThreadRestrictions::SetIOAllowed(true);
-    loopback_server_->HandleCommand(request, &server_status,
-                                    &response_code_large, response);
-    *response_code = static_cast<int>(response_code_large);
-    completion_closure.Run();
-    return;
-  }
-
-  response_proto.set_store_birthday(loopback_server_->GetStoreBirthday());
+        *error_code = net::ERR_NOT_IMPLEMENTED;
+        *response_code = 0;
+        *response = string();
+        completion_closure.Run();
+        return;
+    }
+
+    if (!success) {
+      // TODO(pvalenzuela): Add logging here so that tests have more info about
+      // the failure.
+      *error_code = net::ERR_FAILED;
+      *response_code = 0;
+      *response = string();
+      completion_closure.Run();
+      return;
+    }
+
+    response_proto.set_error_code(sync_pb::SyncEnums::SUCCESS);
+  }
+
+  response_proto.set_store_birthday(GetStoreBirthday());
+
+  *error_code = 0;
+  *response_code = net::HTTP_OK;
   *response = response_proto.SerializeAsString();
   completion_closure.Run();
 }
@@ -131,40 +315,287 @@
   return true;
 }
 
+bool FakeServer::HandleGetUpdatesRequest(
+    const sync_pb::GetUpdatesMessage& get_updates,
+    sync_pb::GetUpdatesResponse* response) {
+  // TODO(pvalenzuela): Implement batching instead of sending all information
+  // at once.
+  response->set_changes_remaining(0);
+
+  auto sieve = base::MakeUnique<UpdateSieve>(get_updates);
+
+  // This folder is called "Synced Bookmarks" by sync and is renamed
+  // "Mobile Bookmarks" by the mobile client UIs.
+  if (get_updates.create_mobile_bookmarks_folder() &&
+      !CreatePermanentBookmarkFolder(kSyncedBookmarksFolderServerTag,
+                                     kSyncedBookmarksFolderName)) {
+    return false;
+  }
+
+  bool send_encryption_keys_based_on_nigori = false;
+  for (EntityMap::const_iterator it = entities_.begin(); it != entities_.end();
+       ++it) {
+    const FakeServerEntity& entity = *it->second;
+    if (sieve->ClientWantsItem(entity)) {
+      sync_pb::SyncEntity* response_entity = response->add_entries();
+      entity.SerializeAsProto(response_entity);
+
+      if (entity.model_type() == syncer::NIGORI) {
+        send_encryption_keys_based_on_nigori =
+            response_entity->specifics().nigori().passphrase_type() ==
+            sync_pb::NigoriSpecifics::KEYSTORE_PASSPHRASE;
+      }
+    }
+  }
+
+  if (send_encryption_keys_based_on_nigori ||
+      get_updates.need_encryption_key()) {
+    for (vector<string>::iterator it = keystore_keys_.begin();
+         it != keystore_keys_.end(); ++it) {
+      response->add_encryption_keys(*it);
+    }
+  }
+
+  sieve->SetProgressMarkers(response);
+  return true;
+}
+
+string FakeServer::CommitEntity(
+    const sync_pb::SyncEntity& client_entity,
+    sync_pb::CommitResponse_EntryResponse* entry_response,
+    const string& client_guid,
+    const string& parent_id) {
+  if (client_entity.version() == 0 && client_entity.deleted()) {
+    return string();
+  }
+
+  std::unique_ptr<FakeServerEntity> entity;
+  if (client_entity.deleted()) {
+    entity = TombstoneEntity::Create(client_entity.id_string(),
+                                     client_entity.client_defined_unique_tag());
+    DeleteChildren(client_entity.id_string());
+  } else if (GetModelType(client_entity) == syncer::NIGORI) {
+    // NIGORI is the only permanent item type that should be updated by the
+    // client.
+    EntityMap::const_iterator iter = entities_.find(client_entity.id_string());
+    CHECK(iter != entities_.end());
+    entity = PermanentEntity::CreateUpdatedNigoriEntity(client_entity,
+                                                        *iter->second);
+  } else if (client_entity.has_client_defined_unique_tag()) {
+    entity = UniqueClientEntity::Create(client_entity);
+  } else {
+    // TODO(pvalenzuela): Validate entity's parent ID.
+    EntityMap::const_iterator iter = entities_.find(client_entity.id_string());
+    if (iter != entities_.end()) {
+      entity = BookmarkEntity::CreateUpdatedVersion(client_entity,
+                                                    *iter->second, parent_id);
+    } else {
+      entity = BookmarkEntity::CreateNew(client_entity, parent_id, client_guid);
+    }
+  }
+
+  if (!entity) {
+    // TODO(pvalenzuela): Add logging so that it is easier to determine why
+    // creation failed.
+    return string();
+  }
+
+  const std::string id = entity->id();
+  SaveEntity(std::move(entity));
+  BuildEntryResponseForSuccessfulCommit(id, entry_response);
+  return id;
+}
+
+void FakeServer::BuildEntryResponseForSuccessfulCommit(
+    const std::string& entity_id,
+    sync_pb::CommitResponse_EntryResponse* entry_response) {
+  EntityMap::const_iterator iter = entities_.find(entity_id);
+  CHECK(iter != entities_.end());
+  const FakeServerEntity& entity = *iter->second;
+  entry_response->set_response_type(sync_pb::CommitResponse::SUCCESS);
+  entry_response->set_id_string(entity.id());
+
+  if (entity.IsDeleted()) {
+    entry_response->set_version(entity.GetVersion() + 1);
+  } else {
+    entry_response->set_version(entity.GetVersion());
+    entry_response->set_name(entity.GetName());
+  }
+}
+
+bool FakeServer::IsChild(const string& id, const string& potential_parent_id) {
+  EntityMap::const_iterator iter = entities_.find(id);
+  if (iter == entities_.end()) {
+    // We've hit an ID (probably the imaginary root entity) that isn't stored
+    // by the server, so it can't be a child.
+    return false;
+  }
+
+  const FakeServerEntity& entity = *iter->second;
+  if (entity.GetParentId() == potential_parent_id)
+    return true;
+
+  // Recursively look up the tree.
+  return IsChild(entity.GetParentId(), potential_parent_id);
+}
+
+void FakeServer::DeleteChildren(const string& id) {
+  std::vector<std::unique_ptr<FakeServerEntity>> tombstones;
+  // Find all the children of id.
+  for (const auto& entity : entities_) {
+    if (IsChild(entity.first, id)) {
+      tombstones.push_back(TombstoneEntity::Create(
+          entity.first, entity.second->client_defined_unique_tag()));
+    }
+  }
+
+  for (auto& tombstone : tombstones) {
+    SaveEntity(std::move(tombstone));
+  }
+}
+
+bool FakeServer::HandleCommitRequest(const sync_pb::CommitMessage& commit,
+                                     const std::string& invalidator_client_id,
+                                     sync_pb::CommitResponse* response) {
+  std::map<string, string> client_to_server_ids;
+  string guid = commit.cache_guid();
+  ModelTypeSet committed_model_types;
+
+  // TODO(pvalenzuela): Add validation of CommitMessage.entries.
+  ::google::protobuf::RepeatedPtrField<sync_pb::SyncEntity>::const_iterator it;
+  for (it = commit.entries().begin(); it != commit.entries().end(); ++it) {
+    sync_pb::CommitResponse_EntryResponse* entry_response =
+        response->add_entryresponse();
+
+    sync_pb::SyncEntity client_entity = *it;
+    string parent_id = client_entity.parent_id_string();
+    if (client_to_server_ids.find(parent_id) != client_to_server_ids.end()) {
+      parent_id = client_to_server_ids[parent_id];
+    }
+
+    const string entity_id =
+        CommitEntity(client_entity, entry_response, guid, parent_id);
+    if (entity_id.empty()) {
+      return false;
+    }
+
+    // Record the ID if it was renamed.
+    if (entity_id != client_entity.id_string()) {
+      client_to_server_ids[client_entity.id_string()] = entity_id;
+    }
+
+    EntityMap::const_iterator iter = entities_.find(entity_id);
+    CHECK(iter != entities_.end());
+    committed_model_types.Put(iter->second->model_type());
+  }
+
+  for (auto& observer : observers_)
+    observer.OnCommit(invalidator_client_id, committed_model_types);
+
+  return true;
+}
+
 std::unique_ptr<base::DictionaryValue>
 FakeServer::GetEntitiesAsDictionaryValue() {
   DCHECK(thread_checker_.CalledOnValidThread());
-  return loopback_server_->GetEntitiesAsDictionaryValue();
+  std::unique_ptr<base::DictionaryValue> dictionary(
+      new base::DictionaryValue());
+
+  // Initialize an empty ListValue for all ModelTypes.
+  ModelTypeSet all_types = ModelTypeSet::All();
+  for (ModelTypeSet::Iterator it = all_types.First(); it.Good(); it.Inc()) {
+    dictionary->Set(ModelTypeToString(it.Get()),
+                    base::MakeUnique<base::ListValue>());
+  }
+
+  for (EntityMap::const_iterator it = entities_.begin(); it != entities_.end();
+       ++it) {
+    const FakeServerEntity& entity = *it->second;
+    if (IsDeletedOrPermanent(entity)) {
+      // Tombstones are ignored as they don't represent current data. Folders
+      // are also ignored as current verification infrastructure does not
+      // consider them.
+      continue;
+    }
+    base::ListValue* list_value;
+    if (!dictionary->GetList(ModelTypeToString(entity.model_type()),
+                             &list_value)) {
+      return std::unique_ptr<base::DictionaryValue>();
+    }
+    // TODO(pvalenzuela): Store more data for each entity so additional
+    // verification can be performed. One example of additional verification
+    // is checking the correctness of the bookmark hierarchy.
+    list_value->AppendString(entity.GetName());
+  }
+
+  return dictionary;
 }
 
 std::vector<sync_pb::SyncEntity> FakeServer::GetSyncEntitiesByModelType(
     ModelType model_type) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  return loopback_server_->GetSyncEntitiesByModelType(model_type);
-}
-
-void FakeServer::InjectEntity(std::unique_ptr<LoopbackServerEntity> entity) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  loopback_server_->SaveEntity(std::move(entity));
+  std::vector<sync_pb::SyncEntity> sync_entities;
+  DCHECK(thread_checker_.CalledOnValidThread());
+  for (EntityMap::const_iterator it = entities_.begin(); it != entities_.end();
+       ++it) {
+    const FakeServerEntity& entity = *it->second;
+    if (!IsDeletedOrPermanent(entity) && entity.model_type() == model_type) {
+      sync_pb::SyncEntity sync_entity;
+      entity.SerializeAsProto(&sync_entity);
+      sync_entities.push_back(sync_entity);
+    }
+  }
+  return sync_entities;
+}
+
+void FakeServer::InjectEntity(std::unique_ptr<FakeServerEntity> entity) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  SaveEntity(std::move(entity));
 }
 
 bool FakeServer::ModifyEntitySpecifics(
     const std::string& id,
     const sync_pb::EntitySpecifics& updated_specifics) {
-  return loopback_server_->ModifyEntitySpecifics(id, updated_specifics);
+  EntityMap::const_iterator iter = entities_.find(id);
+  if (iter == entities_.end() ||
+      iter->second->model_type() !=
+          GetModelTypeFromSpecifics(updated_specifics)) {
+    return false;
+  }
+
+  FakeServerEntity* entity = iter->second.get();
+  entity->SetSpecifics(updated_specifics);
+  UpdateEntityVersion(entity);
+  return true;
 }
 
 bool FakeServer::ModifyBookmarkEntity(
     const std::string& id,
     const std::string& parent_id,
     const sync_pb::EntitySpecifics& updated_specifics) {
-  return loopback_server_->ModifyBookmarkEntity(id, parent_id,
-                                                updated_specifics);
+  EntityMap::const_iterator iter = entities_.find(id);
+  if (iter == entities_.end() ||
+      iter->second->model_type() != syncer::BOOKMARKS ||
+      GetModelTypeFromSpecifics(updated_specifics) != syncer::BOOKMARKS) {
+    return false;
+  }
+
+  BookmarkEntity* entity = static_cast<BookmarkEntity*>(iter->second.get());
+
+  entity->SetParentId(parent_id);
+  entity->SetSpecifics(updated_specifics);
+  if (updated_specifics.has_bookmark()) {
+    entity->SetName(updated_specifics.bookmark().title());
+  }
+  UpdateEntityVersion(entity);
+  return true;
 }
 
 void FakeServer::ClearServerData() {
   DCHECK(thread_checker_.CalledOnValidThread());
-  loopback_server_->ClearServerData();
+  entities_.clear();
+  keystore_keys_.clear();
+  ++store_birthday_;
+  Init();
 }
 
 void FakeServer::SetAuthenticated() {
@@ -242,12 +673,6 @@
   observers_.RemoveObserver(observer);
 }
 
-void FakeServer::OnCommit(const std::string& committer_id,
-                          syncer::ModelTypeSet committed_model_types) {
-  for (auto& observer : observers_)
-    observer.OnCommit(committer_id, committed_model_types);
-}
-
 void FakeServer::EnableNetwork() {
   DCHECK(thread_checker_.CalledOnValidThread());
   network_enabled_ = true;
@@ -258,9 +683,28 @@
   network_enabled_ = false;
 }
 
+std::string FakeServer::GetBookmarkBarFolderId() const {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  for (EntityMap::const_iterator it = entities_.begin(); it != entities_.end();
+       ++it) {
+    FakeServerEntity* entity = it->second.get();
+    if (entity->GetName() == kBookmarkBarFolderName && entity->IsFolder() &&
+        entity->model_type() == syncer::BOOKMARKS) {
+      return entity->id();
+    }
+  }
+  NOTREACHED() << "Bookmark Bar entity not found.";
+  return "";
+}
+
 base::WeakPtr<FakeServer> FakeServer::AsWeakPtr() {
   DCHECK(thread_checker_.CalledOnValidThread());
   return weak_ptr_factory_.GetWeakPtr();
 }
 
+std::string FakeServer::GetStoreBirthday() const {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  return base::Int64ToString(store_birthday_);
+}
+
 }  // namespace fake_server