Cleanup: Remove saved_nigori_state plumbing

It was used for the ClearServerData flow which has been removed. All
the code removed by this CL was efficiently no-op, since
saved_nigori_state was never set.

Bug: 490836
Change-Id: Idcb658e229b983f006937e943baaf9aade5ac8f7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1583735
Commit-Queue: Maksim Moskvitin <mmoskvitin@google.com>
Reviewed-by: Mikel Astiz <mastiz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#654873}

components/sync/driver/glue/sync_engine_backend.cc

@@ -365,7 +365,6 @@ void SyncEngineBackend::DoInitialize(SyncEngine::InitParams params) {
   args.report_unrecoverable_error_function =
       params.report_unrecoverable_error_function;
   args.cancelation_signal = &stop_syncing_signal_;
-  args.saved_nigori_state = std::move(params.saved_nigori_state);
   args.poll_interval = params.poll_interval;
   args.cache_guid = params.cache_guid;
   args.birthday = params.birthday;

components/sync/driver/glue/sync_engine_impl_unittest.cc

@@ -251,7 +251,6 @@ class SyncEngineImplTest : public testing::Test {
     params.delete_sync_data_folder = true;
     params.unrecoverable_error_handler =
         MakeWeakHandle(test_unrecoverable_error_handler_.GetWeakPtr()),
-    params.saved_nigori_state = std::move(saved_nigori_state_);
     sync_prefs_->GetInvalidationVersions(&params.invalidation_versions);
 
     backend_->Initialize(std::move(params));
@@ -325,7 +324,6 @@ class SyncEngineImplTest : public testing::Test {
   ModelTypeSet engine_types_;
   ModelTypeSet enabled_types_;
   std::unique_ptr<NetworkResources> network_resources_;
-  std::unique_ptr<SyncEncryptionHandler::NigoriState> saved_nigori_state_;
   base::OnceClosure quit_loop_;
   testing::NiceMock<MockInvalidationService> invalidator_;
 };

components/sync/driver/profile_sync_service.cc

@@ -507,7 +507,6 @@ void ProfileSyncService::StartUpSlowEngineComponents() {
   params.unrecoverable_error_handler = GetUnrecoverableErrorHandler();
   params.report_unrecoverable_error_function =
       base::BindRepeating(ReportUnrecoverableError, channel_);
-  params.saved_nigori_state = crypto_.TakeSavedNigoriState();
   sync_prefs_.GetInvalidationVersions(&params.invalidation_versions);
   params.poll_interval = sync_prefs_.GetPollInterval();
   if (params.poll_interval.is_zero()) {

components/sync/driver/sync_service_crypto.cc

@@ -353,10 +353,4 @@ SyncServiceCrypto::GetEncryptionObserverProxy() {
       weak_factory_.GetWeakPtr(), base::SequencedTaskRunnerHandle::Get());
 }
 
-std::unique_ptr<SyncEncryptionHandler::NigoriState>
-SyncServiceCrypto::TakeSavedNigoriState() {
-  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
-  return std::move(state_.saved_nigori_state);
-}
-
 }  // namespace syncer

components/sync/driver/sync_service_crypto.h

@@ -68,9 +68,6 @@ class SyncServiceCrypto : public SyncEncryptionHandler::Observer {
   // Creates a proxy observer object that will post calls to this thread.
   std::unique_ptr<SyncEncryptionHandler::Observer> GetEncryptionObserverProxy();
 
-  // Takes the previously saved nigori state; null if there isn't any.
-  std::unique_ptr<SyncEncryptionHandler::NigoriState> TakeSavedNigoriState();
-
   PassphraseRequiredReason passphrase_required_reason() const {
     return state_.passphrase_required_reason;
   }
@@ -115,11 +112,6 @@ class SyncServiceCrypto : public SyncEncryptionHandler::Observer {
     // cancel if they e.g. don't remember their explicit passphrase.
     bool encryption_pending = false;
 
-    // Nigori state after user switching to custom passphrase, saved until
-    // transition steps complete. It will be injected into new engine after sync
-    // restart.
-    std::unique_ptr<SyncEncryptionHandler::NigoriState> saved_nigori_state;
-
     // We cache the cryptographer's pending keys whenever
     // NotifyPassphraseRequired is called. This way, before the UI calls
     // SetDecryptionPassphrase on the syncer, it can avoid the overhead of an

components/sync/engine/sync_engine.h

@@ -74,7 +74,6 @@ class SyncEngine : public ModelTypeConfigurer {
     std::unique_ptr<EngineComponentsFactory> engine_components_factory;
     WeakHandle<UnrecoverableErrorHandler> unrecoverable_error_handler;
     base::Closure report_unrecoverable_error_function;
-    std::unique_ptr<SyncEncryptionHandler::NigoriState> saved_nigori_state;
     std::map<ModelType, int64_t> invalidation_versions;
 
     // Initial authoritative values (usually read from prefs).

components/sync/engine/sync_manager.h

@@ -242,9 +242,6 @@ class SyncManager {
     // Must outlive SyncManager.
     CancelationSignal* cancelation_signal;
 
-    // Optional nigori state to be restored.
-    std::unique_ptr<SyncEncryptionHandler::NigoriState> saved_nigori_state;
-
     // Define the polling interval. Must not be zero.
     base::TimeDelta poll_interval;
 

components/sync/engine_impl/sync_manager_impl.cc

@@ -314,13 +314,6 @@ void SyncManagerImpl::Init(InitArgs* args) {
     return;
   }
 
-  // Now that we have opened the Directory we can restore any previously saved
-  // nigori specifics.
-  if (args->saved_nigori_state) {
-    sync_encryption_handler_->RestoreNigori(*args->saved_nigori_state);
-    args->saved_nigori_state.reset();
-  }
-
   if (args->enable_local_sync_backend) {
     VLOG(1) << "Running against local sync backend.";
     allstatus_.SetLocalBackendFolder(