[Sync] SyncEngine refactor part 1: interfaces.

components/sync/driver/glue/sync_backend_host.h

-// Copyright 2012 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_GLUE_SYNC_BACKEND_HOST_H_
-#define COMPONENTS_SYNC_DRIVER_GLUE_SYNC_BACKEND_HOST_H_
-
-#include <memory>
-#include <string>
-
-#include "base/callback.h"
-#include "base/compiler_specific.h"
-#include "base/macros.h"
-#include "base/single_thread_task_runner.h"
-#include "components/sync/base/model_type.h"
-#include "components/sync/base/weak_handle.h"
-#include "components/sync/driver/backend_data_type_configurer.h"
-#include "components/sync/engine/configure_reason.h"
-#include "components/sync/engine/cycle/sync_cycle_snapshot.h"
-#include "components/sync/engine/shutdown_reason.h"
-#include "components/sync/engine/sync_manager.h"
-#include "components/sync/engine/sync_manager_factory.h"
-
-class GURL;
-
-namespace syncer {
-
-class CancelationSignal;
-class HttpPostProviderFactory;
-class SyncFrontend;
-class SyncManagerFactory;
-class UnrecoverableErrorHandler;
-
-// An API to "host" the top level SyncAPI element.
-//
-// This class handles dispatch of potentially blocking calls to appropriate
-// threads and ensures that the SyncFrontend is only accessed on the UI loop.
-class SyncBackendHost : public BackendDataTypeConfigurer {
- public:
-  typedef SyncStatus Status;
-  typedef base::Callback<std::unique_ptr<HttpPostProviderFactory>(
-      CancelationSignal*)>
-      HttpPostProviderFactoryGetter;
-
-  // Stubs used by implementing classes.
-  SyncBackendHost();
-  ~SyncBackendHost() override;
-
-  // Called on the frontend's thread to kick off asynchronous initialization.
-  // Optionally deletes the "Sync Data" folder during init in order to make
-  // sure we're starting fresh.
-  //
-  // |saved_nigori_state| is optional nigori state to restore from a previous
-  // backend instance. May be null.
-  virtual void Initialize(
-      SyncFrontend* frontend,
-      scoped_refptr<base::SingleThreadTaskRunner> sync_task_runner,
-      const WeakHandle<JsEventHandler>& event_handler,
-      const GURL& service_url,
-      const std::string& sync_user_agent,
-      const SyncCredentials& credentials,
-      bool delete_sync_data_folder,
-      bool enable_local_sync_backend,
-      const base::FilePath& local_sync_backend_folder,
-      std::unique_ptr<SyncManagerFactory> sync_manager_factory,
-      const WeakHandle<UnrecoverableErrorHandler>& unrecoverable_error_handler,
-      const base::Closure& report_unrecoverable_error_function,
-      const HttpPostProviderFactoryGetter& http_post_provider_factory_getter,
-      std::unique_ptr<SyncEncryptionHandler::NigoriState>
-          saved_nigori_state) = 0;
-
-  // Called on the frontend's thread to trigger a refresh.
-  virtual void TriggerRefresh(const ModelTypeSet& types) = 0;
-
-  // Called on the frontend's thread to update SyncCredentials.
-  virtual void UpdateCredentials(const SyncCredentials& credentials) = 0;
-
-  // This starts the SyncerThread running a Syncer object to communicate with
-  // sync servers.  Until this is called, no changes will leave or enter this
-  // browser from the cloud / sync servers.
-  // Called on |frontend_loop_|.
-  virtual void StartSyncingWithServer() = 0;
-
-  // Called on |frontend_loop_| to asynchronously set a new passphrase for
-  // encryption. Note that it is an error to call SetEncryptionPassphrase under
-  // the following circumstances:
-  // - An explicit passphrase has already been set
-  // - |is_explicit| is true and we have pending keys.
-  // When |is_explicit| is false, a couple of things could happen:
-  // - If there are pending keys, we try to decrypt them. If decryption works,
-  //   this acts like a call to SetDecryptionPassphrase. If not, the GAIA
-  //   passphrase passed in is cached so we can re-encrypt with it in future.
-  // - If there are no pending keys, data is encrypted with |passphrase| (this
-  //   is a no-op if data was already encrypted with |passphrase|.)
-  virtual void SetEncryptionPassphrase(const std::string& passphrase,
-                                       bool is_explicit) = 0;
-
-  // Called on |frontend_loop_| to use the provided passphrase to asynchronously
-  // attempt decryption. Returns false immediately if the passphrase could not
-  // be used to decrypt a locally cached copy of encrypted keys; returns true
-  // otherwise. If new encrypted keys arrive during the asynchronous call,
-  // OnPassphraseRequired may be triggered at a later time. It is an error to
-  // call this when there are no pending keys.
-  virtual bool SetDecryptionPassphrase(const std::string& passphrase)
-      WARN_UNUSED_RESULT = 0;
-
-  // Called on |frontend_loop_| to kick off shutdown procedure.  Attempts to cut
-  // short any long-lived or blocking sync thread tasks so that the shutdown on
-  // sync thread task that we're about to post won't have to wait very long.
-  virtual void StopSyncingForShutdown() = 0;
-
-  // Called on |frontend_loop_| to kick off shutdown.
-  // See the implementation and Core::DoShutdown for details.
-  // Must be called *after* StopSyncingForShutdown.
-  virtual void Shutdown(ShutdownReason reason) = 0;
-
-  // Removes all current registrations from the backend on the
-  // InvalidationService.
-  virtual void UnregisterInvalidationIds() = 0;
-
-  // Changes the set of data types that are currently being synced.
-  // The ready_task will be run when configuration is done with the
-  // set of all types that failed configuration (i.e., if its argument
-  // is non-empty, then an error was encountered).
-  // Returns the set of types that are ready to start without needing any
-  // further sync activity.
-  // BackendDataTypeConfigurer implementation.
-  ModelTypeSet ConfigureDataTypes(
-      ConfigureReason reason,
-      const DataTypeConfigStateMap& config_state_map,
-      const base::Callback<void(ModelTypeSet, ModelTypeSet)>& ready_task,
-      const base::Callback<void()>& retry_callback) override = 0;
-
-  // Turns on encryption of all present and future sync data.
-  virtual void EnableEncryptEverything() = 0;
-
-  // Called on |frontend_loop_| to obtain a handle to the UserShare needed for
-  // creating transactions.  Should not be called before we signal
-  // initialization is complete with OnBackendInitialized().
-  virtual UserShare* GetUserShare() const = 0;
-
-  // Called from any thread to obtain current status information in detailed or
-  // summarized form.
-  virtual Status GetDetailedStatus() = 0;
-  virtual SyncCycleSnapshot GetLastCycleSnapshot() const = 0;
-
-  // Determines if the underlying sync engine has made any local changes to
-  // items that have not yet been synced with the server.
-  // ONLY CALL THIS IF OnInitializationComplete was called!
-  virtual bool HasUnsyncedItems() const = 0;
-
-  // Whether or not we are syncing encryption keys.
-  virtual bool IsNigoriEnabled() const = 0;
-
-  // Returns the type of passphrase being used to encrypt data. See
-  // sync_encryption_handler.h.
-  virtual PassphraseType GetPassphraseType() const = 0;
-
-  // If an explicit passphrase is in use, returns the time at which that
-  // passphrase was set (if available).
-  virtual base::Time GetExplicitPassphraseTime() const = 0;
-
-  // True if the cryptographer has any keys available to attempt decryption.
-  // Could mean we've downloaded and loaded Nigori objects, or we bootstrapped
-  // using a token previously received.
-  virtual bool IsCryptographerReady(const BaseTransaction* trans) const = 0;
-
-  virtual void GetModelSafeRoutingInfo(ModelSafeRoutingInfo* out) const = 0;
-
-  // Send a message to the sync thread to persist the Directory to disk.
-  virtual void FlushDirectory() const = 0;
-
-  // Requests that the backend forward to the fronent any protocol events in
-  // its buffer and begin forwarding automatically from now on.  Repeated calls
-  // to this function may result in the same events being emitted several
-  // times.
-  virtual void RequestBufferedProtocolEventsAndEnableForwarding() = 0;
-
-  // Disables protocol event forwarding.
-  virtual void DisableProtocolEventForwarding() = 0;
-
-  // Enables the sending of directory type debug counters.  Also, for every
-  // time it is called, it makes an explicit request that updates to an update
-  // for all counters be emitted.
-  virtual void EnableDirectoryTypeDebugInfoForwarding() = 0;
-
-  // Disables the sending of directory type debug counters.
-  virtual void DisableDirectoryTypeDebugInfoForwarding() = 0;
-
-  // Triggers sync cycle to update |types|.
-  virtual void RefreshTypesForTest(ModelTypeSet types) = 0;
-
-  // See SyncManager::ClearServerData.
-  virtual void ClearServerData(
-      const SyncManager::ClearServerDataCallback& callback) = 0;
-
-  // Notify the syncer that the cookie jar has changed.
-  // See SyncManager::OnCookieJarChanged.
-  virtual void OnCookieJarChanged(bool account_mismatch, bool empty_jar) = 0;
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(SyncBackendHost);
-};
-
-}  // namespace syncer
-
-#endif  // COMPONENTS_SYNC_DRIVER_GLUE_SYNC_BACKEND_HOST_H_