Refactor SyncBackendHost

chrome/browser/sync/glue/sync_backend_host_core.cc

+// Copyright 2013 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/sync/glue/sync_backend_host_core.h"
+
+#include "base/command_line.h"
+#include "base/file_util.h"
+#include "base/metrics/histogram.h"
+#include "chrome/browser/sync/glue/device_info.h"
+#include "chrome/browser/sync/glue/sync_backend_registrar.h"
+#include "chrome/browser/sync/glue/synced_device_tracker.h"
+#include "chrome/common/chrome_switches.h"
+#include "chrome/common/chrome_version_info.h"
+#include "sync/internal_api/public/http_post_provider_factory.h"
+#include "sync/internal_api/public/internal_components_factory.h"
+#include "sync/internal_api/public/sessions/sync_session_snapshot.h"
+#include "sync/internal_api/public/sync_manager.h"
+#include "sync/internal_api/public/sync_manager_factory.h"
+
+// Helper macros to log with the syncer thread name; useful when there
+// are multiple syncers involved.
+
+#define SLOG(severity) LOG(severity) << name_ << ": "
+
+#define SDVLOG(verbose_level) DVLOG(verbose_level) << name_ << ": "
+
+static const int kSaveChangesIntervalSeconds = 10;
+
+namespace syncer {
+class InternalComponentsFactory;
+}  // namespace syncer
+
+namespace {
+
+// Enums for UMAs.
+enum SyncBackendInitState {
+    SETUP_COMPLETED_FOUND_RESTORED_TYPES = 0,
+    SETUP_COMPLETED_NO_RESTORED_TYPES,
+    FIRST_SETUP_NO_RESTORED_TYPES,
+    FIRST_SETUP_RESTORED_TYPES,
+    SYNC_BACKEND_INIT_STATE_COUNT
+};
+
+}  // namespace
+
+namespace browser_sync {
+
+DoInitializeOptions::DoInitializeOptions(
+    base::MessageLoop* sync_loop,
+    SyncBackendRegistrar* registrar,
+    const syncer::ModelSafeRoutingInfo& routing_info,
+    const std::vector<syncer::ModelSafeWorker*>& workers,
+    const scoped_refptr<syncer::ExtensionsActivity>& extensions_activity,
+    const syncer::WeakHandle<syncer::JsEventHandler>& event_handler,
+    const GURL& service_url,
+    scoped_ptr<syncer::HttpPostProviderFactory> http_bridge_factory,
+    const syncer::SyncCredentials& credentials,
+    const std::string& invalidator_client_id,
+    scoped_ptr<syncer::SyncManagerFactory> sync_manager_factory,
+    bool delete_sync_data_folder,
+    const std::string& restored_key_for_bootstrapping,
+    const std::string& restored_keystore_key_for_bootstrapping,
+    scoped_ptr<syncer::InternalComponentsFactory> internal_components_factory,
+    scoped_ptr<syncer::UnrecoverableErrorHandler> unrecoverable_error_handler,
+    syncer::ReportUnrecoverableErrorFunction
+        report_unrecoverable_error_function)
+    : sync_loop(sync_loop),
+      registrar(registrar),
+      routing_info(routing_info),
+      workers(workers),
+      extensions_activity(extensions_activity),
+      event_handler(event_handler),
+      service_url(service_url),
+      http_bridge_factory(http_bridge_factory.Pass()),
+      credentials(credentials),
+      invalidator_client_id(invalidator_client_id),
+      sync_manager_factory(sync_manager_factory.Pass()),
+      delete_sync_data_folder(delete_sync_data_folder),
+      restored_key_for_bootstrapping(restored_key_for_bootstrapping),
+      restored_keystore_key_for_bootstrapping(
+          restored_keystore_key_for_bootstrapping),
+      internal_components_factory(internal_components_factory.Pass()),
+      unrecoverable_error_handler(unrecoverable_error_handler.Pass()),
+      report_unrecoverable_error_function(
+          report_unrecoverable_error_function) {
+}
+
+DoInitializeOptions::~DoInitializeOptions() {}
+
+DoConfigureSyncerTypes::DoConfigureSyncerTypes() {}
+
+DoConfigureSyncerTypes::~DoConfigureSyncerTypes() {}
+
+SyncBackendHostCore::SyncBackendHostCore(
+    const std::string& name,
+    const base::FilePath& sync_data_folder_path,
+    bool has_sync_setup_completed,
+    const base::WeakPtr<SyncBackendHostImpl>& backend)
+    : name_(name),
+      sync_data_folder_path_(sync_data_folder_path),
+      host_(backend),
+      sync_loop_(NULL),
+      registrar_(NULL),
+      has_sync_setup_completed_(has_sync_setup_completed),
+      weak_ptr_factory_(this) {
+  DCHECK(backend.get());
+}
+
+SyncBackendHostCore::~SyncBackendHostCore() {
+  DCHECK(!sync_manager_.get());
+}
+
+void SyncBackendHostCore::OnSyncCycleCompleted(
+    const syncer::sessions::SyncSessionSnapshot& snapshot) {
+  if (!sync_loop_)
+    return;
+  DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
+
+  host_.Call(
+      FROM_HERE,
+      &SyncBackendHostImpl::HandleSyncCycleCompletedOnFrontendLoop,
+      snapshot);
+}
+
+void SyncBackendHostCore::DoRefreshTypes(syncer::ModelTypeSet types) {
+  DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
+  sync_manager_->RefreshTypes(types);
+}
+
+void SyncBackendHostCore::OnControlTypesDownloadRetry() {
+  host_.Call(FROM_HERE,
+             &SyncBackendHostImpl::HandleControlTypesDownloadRetry);
+}
+
+void SyncBackendHostCore::OnInitializationComplete(
+    const syncer::WeakHandle<syncer::JsBackend>& js_backend,
+    const syncer::WeakHandle<syncer::DataTypeDebugInfoListener>&
+        debug_info_listener,
+    bool success,
+    const syncer::ModelTypeSet restored_types) {
+  DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
+
+  if (!success) {
+    DoDestroySyncManager();
+    host_.Call(FROM_HERE,
+               &SyncBackendHostImpl::HandleInitializationFailureOnFrontendLoop);
+    return;
+  }
+
+  // Register for encryption related changes now. We have to do this before
+  // the initializing downloading control types or initializing the encryption
+  // handler in order to receive notifications triggered during encryption
+  // startup.
+  sync_manager_->GetEncryptionHandler()->AddObserver(this);
+
+  // Sync manager initialization is complete, so we can schedule recurring
+  // SaveChanges.
+  sync_loop_->PostTask(FROM_HERE,
+                       base::Bind(&SyncBackendHostCore::StartSavingChanges,
+                                  weak_ptr_factory_.GetWeakPtr()));
+
+  // Hang on to these for a while longer.  We're not ready to hand them back to
+  // the UI thread yet.
+  js_backend_ = js_backend;
+  debug_info_listener_ = debug_info_listener;
+
+  // Track whether or not sync DB and preferences were in sync.
+  SyncBackendInitState backend_init_state;
+  if (has_sync_setup_completed_ && !restored_types.Empty()) {
+    backend_init_state = SETUP_COMPLETED_FOUND_RESTORED_TYPES;
+  } else if (has_sync_setup_completed_ && restored_types.Empty()) {
+    backend_init_state = SETUP_COMPLETED_NO_RESTORED_TYPES;
+  } else if (!has_sync_setup_completed_ && restored_types.Empty()) {
+    backend_init_state = FIRST_SETUP_NO_RESTORED_TYPES;
+  } else { // (!has_sync_setup_completed_ && !restored_types.Empty())
+    backend_init_state = FIRST_SETUP_RESTORED_TYPES;
+  }
+
+  UMA_HISTOGRAM_ENUMERATION("Sync.BackendInitializeRestoreState",
+                            backend_init_state,
+                            SYNC_BACKEND_INIT_STATE_COUNT);
+
+  // Before proceeding any further, we need to download the control types and
+  // purge any partial data (ie. data downloaded for a type that was on its way
+  // to being initially synced, but didn't quite make it.).  The following
+  // configure cycle will take care of this.  It depends on the registrar state
+  // which we initialize below to ensure that we don't perform any downloads if
+  // all control types have already completed their initial sync.
+  registrar_->SetInitialTypes(restored_types);
+
+  syncer::ConfigureReason reason =
+      restored_types.Empty() ?
+       syncer::CONFIGURE_REASON_NEW_CLIENT :
+       syncer::CONFIGURE_REASON_NEWLY_ENABLED_DATA_TYPE;
+
+  syncer::ModelTypeSet new_control_types = registrar_->ConfigureDataTypes(
+      syncer::ControlTypes(), syncer::ModelTypeSet());
+  syncer::ModelSafeRoutingInfo routing_info;
+  registrar_->GetModelSafeRoutingInfo(&routing_info);
+  SDVLOG(1) << "Control Types "
+            << syncer::ModelTypeSetToString(new_control_types)
+            << " added; calling ConfigureSyncer";
+
+  syncer::ModelTypeSet types_to_purge =
+      syncer::Difference(syncer::ModelTypeSet::All(),
+                         GetRoutingInfoTypes(routing_info));
+
+  sync_manager_->ConfigureSyncer(
+      reason,
+      new_control_types,
+      types_to_purge,
+      syncer::ModelTypeSet(),
+      syncer::ModelTypeSet(),
+      routing_info,
+      base::Bind(&SyncBackendHostCore::DoInitialProcessControlTypes,
+                 weak_ptr_factory_.GetWeakPtr()),
+      base::Bind(&SyncBackendHostCore::OnControlTypesDownloadRetry,
+                 weak_ptr_factory_.GetWeakPtr()));
+}
+
+void SyncBackendHostCore::OnConnectionStatusChange(
+    syncer::ConnectionStatus status) {
+  if (!sync_loop_)
+    return;
+  DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
+  host_.Call(
+      FROM_HERE,
+      &SyncBackendHostImpl::HandleConnectionStatusChangeOnFrontendLoop, status);
+}
+
+void SyncBackendHostCore::OnPassphraseRequired(
+    syncer::PassphraseRequiredReason reason,
+    const sync_pb::EncryptedData& pending_keys) {
+  if (!sync_loop_)
+    return;
+  DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
+  host_.Call(
+      FROM_HERE,
+      &SyncBackendHostImpl::NotifyPassphraseRequired, reason, pending_keys);
+}
+
+void SyncBackendHostCore::OnPassphraseAccepted() {
+  if (!sync_loop_)
+    return;
+  DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
+  host_.Call(
+      FROM_HERE,
+      &SyncBackendHostImpl::NotifyPassphraseAccepted);
+}
+
+void SyncBackendHostCore::OnBootstrapTokenUpdated(
+    const std::string& bootstrap_token,
+    syncer::BootstrapTokenType type) {
+  if (!sync_loop_)
+    return;
+  DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
+  host_.Call(FROM_HERE,
+             &SyncBackendHostImpl::PersistEncryptionBootstrapToken,
+             bootstrap_token,
+             type);
+}
+
+void SyncBackendHostCore::OnStopSyncingPermanently() {
+  if (!sync_loop_)
+    return;
+  DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
+  host_.Call(
+      FROM_HERE,
+      &SyncBackendHostImpl::HandleStopSyncingPermanentlyOnFrontendLoop);
+}
+
+void SyncBackendHostCore::OnEncryptedTypesChanged(
+    syncer::ModelTypeSet encrypted_types,
+    bool encrypt_everything) {
+  if (!sync_loop_)
+    return;
+  DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
+  // NOTE: We're in a transaction.
+  host_.Call(
+      FROM_HERE,
+      &SyncBackendHostImpl::NotifyEncryptedTypesChanged,
+      encrypted_types, encrypt_everything);
+}
+
+void SyncBackendHostCore::OnEncryptionComplete() {
+  if (!sync_loop_)
+    return;
+  DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
+  // NOTE: We're in a transaction.
+  host_.Call(
+      FROM_HERE,
+      &SyncBackendHostImpl::NotifyEncryptionComplete);
+}
+
+void SyncBackendHostCore::OnCryptographerStateChanged(
+    syncer::Cryptographer* cryptographer) {
+  // Do nothing.
+}
+
+void SyncBackendHostCore::OnPassphraseTypeChanged(
+    syncer::PassphraseType type, base::Time passphrase_time) {
+  host_.Call(
+      FROM_HERE,
+      &SyncBackendHostImpl::HandlePassphraseTypeChangedOnFrontendLoop,
+      type, passphrase_time);
+}
+
+void SyncBackendHostCore::OnActionableError(
+    const syncer::SyncProtocolError& sync_error) {
+  if (!sync_loop_)
+    return;
+  DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
+  host_.Call(
+      FROM_HERE,
+      &SyncBackendHostImpl::HandleActionableErrorEventOnFrontendLoop,
+      sync_error);
+}
+
+void SyncBackendHostCore::DoOnInvalidatorStateChange(
+    syncer::InvalidatorState state) {
+  DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
+  sync_manager_->OnInvalidatorStateChange(state);
+}
+
+void SyncBackendHostCore::DoOnIncomingInvalidation(
+    syncer::ObjectIdInvalidationMap invalidation_map) {
+  DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
+  sync_manager_->OnIncomingInvalidation(invalidation_map);
+}
+
+void SyncBackendHostCore::DoInitialize(
+    scoped_ptr<DoInitializeOptions> options) {
+  DCHECK(!sync_loop_);
+  sync_loop_ = options->sync_loop;
+  DCHECK(sync_loop_);
+
+  // Finish initializing the HttpBridgeFactory.  We do this here because
+  // building the user agent may block on some platforms.
+  chrome::VersionInfo version_info;
+  options->http_bridge_factory->Init(
+      DeviceInfo::MakeUserAgentForSyncApi(version_info));
+
+  // Blow away the partial or corrupt sync data folder before doing any more
+  // initialization, if necessary.
+  if (options->delete_sync_data_folder) {
+    DeleteSyncDataFolder();
+  }
+
+  // Make sure that the directory exists before initializing the backend.
+  // If it already exists, this will do no harm.
+  if (!file_util::CreateDirectory(sync_data_folder_path_)) {
+    DLOG(FATAL) << "Sync Data directory creation failed.";
+  }
+
+  DCHECK(!registrar_);
+  registrar_ = options->registrar;
+  DCHECK(registrar_);
+
+  sync_manager_ = options->sync_manager_factory->CreateSyncManager(name_);
+  sync_manager_->AddObserver(this);
+  sync_manager_->Init(sync_data_folder_path_,
+                      options->event_handler,
+                      options->service_url.host() + options->service_url.path(),
+                      options->service_url.EffectiveIntPort(),
+                      options->service_url.SchemeIsSecure(),
+                      options->http_bridge_factory.Pass(),
+                      options->workers,
+                      options->extensions_activity,
+                      options->registrar /* as SyncManager::ChangeDelegate */,
+                      options->credentials,
+                      options->invalidator_client_id,
+                      options->restored_key_for_bootstrapping,
+                      options->restored_keystore_key_for_bootstrapping,
+                      options->internal_components_factory.get(),
+                      &encryptor_,
+                      options->unrecoverable_error_handler.Pass(),
+                      options->report_unrecoverable_error_function,
+                      &stop_syncing_signal_);
+
+  // |sync_manager_| may end up being NULL here in tests (in
+  // synchronous initialization mode).
+  //
+  // TODO(akalin): Fix this behavior (see http://crbug.com/140354).
+  if (sync_manager_) {
+    // Now check the command line to see if we need to simulate an
+    // unrecoverable error for testing purpose. Note the error is thrown
+    // only if the initialization succeeded. Also it makes sense to use this
+    // flag only when restarting the browser with an account already setup. If
+    // you use this before setting up the setup would not succeed as an error
+    // would be encountered.
+    if (CommandLine::ForCurrentProcess()->HasSwitch(
+            switches::kSyncThrowUnrecoverableError)) {
+      sync_manager_->ThrowUnrecoverableError();
+    }
+  }
+}
+
+void SyncBackendHostCore::DoUpdateCredentials(
+    const syncer::SyncCredentials& credentials) {
+  DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
+  // UpdateCredentials can be called during backend initialization, possibly
+  // when backend initialization has failed but hasn't notified the UI thread
+  // yet. In that case, the sync manager may have been destroyed on the sync
+  // thread before this task was executed, so we do nothing.
+  if (sync_manager_) {
+    sync_manager_->UpdateCredentials(credentials);
+  }
+}
+
+void SyncBackendHostCore::DoStartSyncing(
+    const syncer::ModelSafeRoutingInfo& routing_info) {
+  DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
+  sync_manager_->StartSyncingNormally(routing_info);
+}
+
+void SyncBackendHostCore::DoSetEncryptionPassphrase(
+    const std::string& passphrase,
+    bool is_explicit) {
+  DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
+  sync_manager_->GetEncryptionHandler()->SetEncryptionPassphrase(
+      passphrase, is_explicit);
+}
+
+void SyncBackendHostCore::DoInitialProcessControlTypes() {
+  DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
+
+  DVLOG(1) << "Initilalizing Control Types";
+
+  // Initialize encryption.
+  sync_manager_->GetEncryptionHandler()->Init();
+
+  // Note: experiments are currently handled via SBH::AddExperimentalTypes,
+  // which is called at the end of every sync cycle.
+  // TODO(zea): eventually add an experiment handler and initialize it here.
+
+  if (!sync_manager_->GetUserShare()) {  // NULL in some tests.
+    DVLOG(1) << "Skipping initialization of DeviceInfo";
+    host_.Call(
+        FROM_HERE,
+        &SyncBackendHostImpl::HandleInitializationFailureOnFrontendLoop);
+    return;
+  }
+
+  if (!sync_manager_->InitialSyncEndedTypes().HasAll(syncer::ControlTypes())) {
+    LOG(ERROR) << "Failed to download control types";
+    host_.Call(
+        FROM_HERE,
+        &SyncBackendHostImpl::HandleInitializationFailureOnFrontendLoop);
+    return;
+  }
+
+  // Initialize device info. This is asynchronous on some platforms, so we
+  // provide a callback for when it finishes.
+  synced_device_tracker_.reset(
+      new SyncedDeviceTracker(sync_manager_->GetUserShare(),
+                              sync_manager_->cache_guid()));
+  synced_device_tracker_->InitLocalDeviceInfo(
+      base::Bind(&SyncBackendHostCore::DoFinishInitialProcessControlTypes,
+                 weak_ptr_factory_.GetWeakPtr()));
+}
+
+void SyncBackendHostCore::DoFinishInitialProcessControlTypes() {
+  registrar_->ActivateDataType(syncer::DEVICE_INFO,
+                               syncer::GROUP_PASSIVE,
+                               synced_device_tracker_.get(),
+                               sync_manager_->GetUserShare());
+
+  host_.Call(
+      FROM_HERE,
+      &SyncBackendHostImpl::HandleInitializationSuccessOnFrontendLoop,
+      js_backend_,
+      debug_info_listener_);
+
+  js_backend_.Reset();
+  debug_info_listener_.Reset();
+}
+
+void SyncBackendHostCore::DoSetDecryptionPassphrase(
+    const std::string& passphrase) {
+  DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
+  sync_manager_->GetEncryptionHandler()->SetDecryptionPassphrase(
+      passphrase);
+}
+
+void SyncBackendHostCore::DoEnableEncryptEverything() {
+  DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
+  sync_manager_->GetEncryptionHandler()->EnableEncryptEverything();
+}
+
+void SyncBackendHostCore::ShutdownOnUIThread() {
+  // This will cut short any blocking network tasks, cut short any in-progress
+  // sync cycles, and prevent the creation of new blocking network tasks and new
+  // sync cycles.  If there was an in-progress network request, it would have
+  // had a reference to the RequestContextGetter.  This reference will be
+  // dropped by the time this function returns.
+  //
+  // It is safe to call this even if Sync's backend classes have not been
+  // initialized yet.  Those classes will receive the message when the sync
+  // thread finally getes around to constructing them.
+  stop_syncing_signal_.Signal();
+
+  // This will drop the HttpBridgeFactory's reference to the
+  // RequestContextGetter.  Once this has been called, the HttpBridgeFactory can
+  // no longer be used to create new HttpBridge instances.  We can get away with
+  // this because the stop_syncing_signal_ has already been signalled, which
+  // guarantees that the ServerConnectionManager will no longer attempt to
+  // create new connections.
+  release_request_context_signal_.Signal();
+}
+
+void SyncBackendHostCore::DoShutdown(bool sync_disabled) {
+  DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
+
+  // It's safe to do this even if the type was never activated.
+  registrar_->DeactivateDataType(syncer::DEVICE_INFO);
+  synced_device_tracker_.reset();
+
+  DoDestroySyncManager();
+
+  registrar_ = NULL;
+
+  if (sync_disabled)
+    DeleteSyncDataFolder();
+
+  host_.Reset();
+  weak_ptr_factory_.InvalidateWeakPtrs();
+}
+
+void SyncBackendHostCore::DoDestroySyncManager() {
+  DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
+  if (sync_manager_) {
+    save_changes_timer_.reset();
+    sync_manager_->RemoveObserver(this);
+    sync_manager_->ShutdownOnSyncThread();
+    sync_manager_.reset();
+  }
+}
+
+void SyncBackendHostCore::DoConfigureSyncer(
+    syncer::ConfigureReason reason,
+    const DoConfigureSyncerTypes& config_types,
+    const syncer::ModelSafeRoutingInfo routing_info,
+    const base::Callback<void(syncer::ModelTypeSet,
+                              syncer::ModelTypeSet)>& ready_task,
+    const base::Closure& retry_callback) {
+  DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
+  sync_manager_->ConfigureSyncer(
+      reason,
+      config_types.to_download,
+      config_types.to_purge,
+      config_types.to_journal,
+      config_types.to_unapply,
+      routing_info,
+      base::Bind(&SyncBackendHostCore::DoFinishConfigureDataTypes,
+                 weak_ptr_factory_.GetWeakPtr(),
+                 config_types.to_download,
+                 ready_task),
+      base::Bind(&SyncBackendHostCore::DoRetryConfiguration,
+                 weak_ptr_factory_.GetWeakPtr(),
+                 retry_callback));
+}
+
+void SyncBackendHostCore::DoFinishConfigureDataTypes(
+    syncer::ModelTypeSet types_to_config,
+    const base::Callback<void(syncer::ModelTypeSet,
+                              syncer::ModelTypeSet)>& ready_task) {
+  DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
+
+  // Update the enabled types for the bridge and sync manager.
+  syncer::ModelSafeRoutingInfo routing_info;
+  registrar_->GetModelSafeRoutingInfo(&routing_info);
+  syncer::ModelTypeSet enabled_types = GetRoutingInfoTypes(routing_info);
+  enabled_types.RemoveAll(syncer::ProxyTypes());
+
+  const syncer::ModelTypeSet failed_configuration_types =
+      Difference(types_to_config, sync_manager_->InitialSyncEndedTypes());
+  const syncer::ModelTypeSet succeeded_configuration_types =
+      Difference(types_to_config, failed_configuration_types);
+  host_.Call(FROM_HERE,
+             &SyncBackendHostImpl::FinishConfigureDataTypesOnFrontendLoop,
+             enabled_types,
+             succeeded_configuration_types,
+             failed_configuration_types,
+             ready_task);
+}
+
+void SyncBackendHostCore::DoRetryConfiguration(
+    const base::Closure& retry_callback) {
+  DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
+  host_.Call(FROM_HERE,
+             &SyncBackendHostImpl::RetryConfigurationOnFrontendLoop,
+             retry_callback);
+}
+
+void SyncBackendHostCore::DeleteSyncDataFolder() {
+  DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
+  if (base::DirectoryExists(sync_data_folder_path_)) {
+    if (!base::DeleteFile(sync_data_folder_path_, true))
+      SLOG(DFATAL) << "Could not delete the Sync Data folder.";
+  }
+}
+
+void SyncBackendHostCore::StartSavingChanges() {
+  // We may already be shut down.
+  if (!sync_loop_)
+    return;
+  DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
+  DCHECK(!save_changes_timer_.get());
+  save_changes_timer_.reset(new base::RepeatingTimer<SyncBackendHostCore>());
+  save_changes_timer_->Start(FROM_HERE,
+      base::TimeDelta::FromSeconds(kSaveChangesIntervalSeconds),
+      this, &SyncBackendHostCore::SaveChanges);
+}
+
+void SyncBackendHostCore::SaveChanges() {
+  DCHECK_EQ(base::MessageLoop::current(), sync_loop_);
+  sync_manager_->SaveChanges();
+}
+
+}  // namespace browser_sync
+