Delete blimp/helium and remove references to it from dependent targets

blimp/helium/syncable.h

-// Copyright 2016 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 BLIMP_HELIUM_SYNCABLE_H_
-#define BLIMP_HELIUM_SYNCABLE_H_
-
-#include <stdint.h>
-#include <memory>
-
-#include "base/callback.h"
-#include "base/macros.h"
-#include "blimp/helium/result.h"
-#include "blimp/helium/version_vector.h"
-
-namespace blimp {
-namespace helium {
-
-// LazySyncable is something that supports creating and restoring Changesets.
-// These objects exchange Changesets between the client and server to keep
-// their peer counterparts eventually synchronized.
-//
-// It provides the following things:
-// 1. Mapping: There is a one-to-one relationship between instances on the
-// client and instances on the engine.
-// 2. Consistency: The values stored in client-engine pairs should eventually be
-// equal.
-//
-// LazySyncable is a base interface that is used for both self contained objects
-// (i.e. simple register) and objects which are disconnected replicas
-// of external state. In the latter case, the method PrepareToCreateChangeset()
-// is used to tell the LazySyncable to replicate its state asynchronously.
-template <typename ChangesetType>
-class LazySyncable {
- public:
-  // Easy access to the type through which Changesets are serialized for this
-  // Syncable.
-  using Changeset = ChangesetType;
-
-  virtual ~LazySyncable() = default;
-
-  // Serializes a description of changes between |from| and the current state
-  // into the specified |output| changeset. Note that the Sync layer will use
-  // GetRevision() to determine the end-revision for the Changeset, so the
-  // Syncable must ensure that GetRevision() is incremented at least on the next
-  // modification after this call.
-  virtual std::unique_ptr<ChangesetType> CreateChangeset(
-      Revision from) const = 0;
-
-  // Reads and applies a Changeset originating from the peer counterpart of
-  // this Syncable. Failure to apply the changeset should result in a CHECK
-  // failure.
-  virtual void ApplyChangeset(const ChangesetType& changeset) = 0;
-
-  // Sets the callback that the Syncable should invoke immediately after being
-  // modified
-  // locally (e.g. LwwRegister::Set() will call it before returning).
-  virtual void SetLocalUpdateCallback(
-      const base::Closure& local_update_callback) = 0;
-
-  // Returns true if |changeset| is semantically correct and can be
-  // Applied() to the state of |this|.
-  virtual bool ValidateChangeset(const ChangesetType& changeset) const {
-    return true;
-  }
-
-  // Allows the Syncable to release book-keeping state related to Revisions
-  // prior to |before|. State relating to Revisions |before| and later must be
-  // retained.
-  virtual void ReleaseBefore(Revision checkpoint) = 0;
-
-  // Returns the current Revision of this Syncable. If the returned Revision is
-  // zero then the Syncable is newly-created and has not yet been modified.
-  virtual Revision GetRevision() const = 0;
-
-  // Called when the Sync layer is ready to request a Changeset for this
-  // Syncable, to allow for external state to be pulled into the Syncable ready
-  // for synchronous serialization.
-  virtual void PrepareToCreateChangeset(Revision from, base::Closure done) = 0;
-};
-
-template <typename ChangesetType>
-class Syncable : public LazySyncable<ChangesetType> {
- public:
-  // LazySyncable implementation.
-  void PrepareToCreateChangeset(Revision from, base::Closure done) override {
-    // Default no-op implementation.
-    done.Run();
-  }
-};
-
-}  // namespace helium
-}  // namespace blimp
-
-#endif  // BLIMP_HELIUM_SYNCABLE_H_