[Sync] SyncEngine refactor part 1: interfaces.

components/sync/driver/sync_frontend.h

-// Copyright 2014 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.
-
-#ifndef COMPONENTS_SYNC_DRIVER_SYNC_FRONTEND_H_
-#define COMPONENTS_SYNC_DRIVER_SYNC_FRONTEND_H_
-
-#include <string>
-
-#include "components/sync/base/model_type.h"
-#include "components/sync/base/weak_handle.h"
-#include "components/sync/engine/sync_encryption_handler.h"
-#include "components/sync/engine/sync_manager.h"
-#include "components/sync/protocol/sync_protocol_error.h"
-
-namespace sync_pb {
-class EncryptedData;
-}  // namespace sync_pb
-
-namespace syncer {
-
-class DataTypeDebugInfoListener;
-class JsBackend;
-class ProtocolEvent;
-struct CommitCounters;
-struct StatusCounters;
-struct UpdateCounters;
-
-// SyncFrontend is the interface used by SyncBackendHost to communicate with
-// the entity that created it and, presumably, is interested in sync-related
-// activity.
-// NOTE: All methods will be invoked by a SyncBackendHost on the same thread
-// used to create that SyncBackendHost.
-class SyncFrontend {
- public:
-  SyncFrontend();
-  virtual ~SyncFrontend();
-
-  // The backend has completed initialization and it is now ready to
-  // accept and process changes.  If success is false, initialization
-  // wasn't able to be completed and should be retried.
-  //
-  // |js_backend| is what about:sync interacts with; it's different
-  // from the 'Backend' in 'OnBackendInitialized' (unfortunately).  It
-  // is initialized only if |success| is true.
-  virtual void OnBackendInitialized(
-      const WeakHandle<JsBackend>& js_backend,
-      const WeakHandle<DataTypeDebugInfoListener>& debug_info_listener,
-      const std::string& cache_guid,
-      bool success) = 0;
-
-  // The backend queried the server recently and received some updates.
-  virtual void OnSyncCycleCompleted() = 0;
-
-  // Informs the frontned of some network event.  These notifications are
-  // disabled by default and must be enabled through an explicit request to the
-  // SyncBackendHost.
-  //
-  // It's disabld by default to avoid copying data across threads when no one
-  // is listening for it.
-  virtual void OnProtocolEvent(const ProtocolEvent& event) = 0;
-
-  // Called when we receive an updated commit counter for a directory type.
-  //
-  // Disabled by default.  Enable by calling
-  // EnableDirectoryTypeDebugInfoForwarding() on the backend.
-  virtual void OnDirectoryTypeCommitCounterUpdated(
-      ModelType type,
-      const CommitCounters& counters) = 0;
-
-  // Called when we receive an updated update counter for a directory type.
-  //
-  // Disabled by default.  Enable by calling
-  // EnableDirectoryTypeDebugInfoForwarding() on the backend.
-  virtual void OnDirectoryTypeUpdateCounterUpdated(
-      ModelType type,
-      const UpdateCounters& counters) = 0;
-
-  // Called when we receive an updated status counter for a datatype.
-  //
-  // Disabled by default.  Enable by calling
-  // EnableDirectoryTypeDebugInfoForwarding() on the backend.
-  virtual void OnDatatypeStatusCounterUpdated(
-      ModelType type,
-      const StatusCounters& counters) = 0;
-
-  // The status of the connection to the sync server has changed.
-  virtual void OnConnectionStatusChange(ConnectionStatus status) = 0;
-
-  // The syncer requires a passphrase to decrypt sensitive updates. This is
-  // called when the first sensitive data type is setup by the user and anytime
-  // the passphrase is changed by another synced client. |reason| denotes why
-  // the passphrase was required. |pending_keys| is a copy of the
-  // cryptographer's pending keys to be passed on to the frontend in order to
-  // be cached.
-  virtual void OnPassphraseRequired(
-      PassphraseRequiredReason reason,
-      const sync_pb::EncryptedData& pending_keys) = 0;
-
-  // Called when the passphrase provided by the user is
-  // accepted. After this is called, updates to sensitive nodes are
-  // encrypted using the accepted passphrase.
-  virtual void OnPassphraseAccepted() = 0;
-
-  // Called when the set of encrypted types or the encrypt everything
-  // flag has been changed.  Note that encryption isn't complete until
-  // the OnEncryptionComplete() notification has been sent (see
-  // below).
-  //
-  // |encrypted_types| will always be a superset of
-  // Cryptographer::SensitiveTypes().  If |encrypt_everything| is
-  // true, |encrypted_types| will be the set of all known types.
-  //
-  // Until this function is called, observers can assume that the set
-  // of encrypted types is Cryptographer::SensitiveTypes() and that
-  // the encrypt everything flag is false.
-  virtual void OnEncryptedTypesChanged(ModelTypeSet encrypted_types,
-                                       bool encrypt_everything) = 0;
-
-  // Called after we finish encrypting the current set of encrypted
-  // types.
-  virtual void OnEncryptionComplete() = 0;
-
-  // Called to perform migration of |types|.
-  virtual void OnMigrationNeededForTypes(ModelTypeSet types) = 0;
-
-  // Inform the Frontend that new datatypes are available for registration.
-  virtual void OnExperimentsChanged(const Experiments& experiments) = 0;
-
-  // Called when the sync cycle returns there is an user actionable error.
-  virtual void OnActionableError(const SyncProtocolError& error) = 0;
-
-  // Called when the user of this device enables passphrase encryption.
-  //
-  // |nigori_state| contains the new (post custom passphrase) encryption keys
-  // and can be used to restore SyncEncryptionHandler's state across sync
-  // backend instances. See also SyncEncryptionHandlerImpl::RestoreNigori.
-  virtual void OnLocalSetPassphraseEncryption(
-      const SyncEncryptionHandler::NigoriState& nigori_state) = 0;
-};
-
-}  // namespace syncer
-
-#endif  // COMPONENTS_SYNC_DRIVER_SYNC_FRONTEND_H_