[Sync] Move //sync to //components/sync.

sync/internal_api/public/base/invalidation_interface.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 SYNC_INTERNAL_API_PUBLIC_BASE_INVALIDATION_INTERFACE_H_
-#define SYNC_INTERNAL_API_PUBLIC_BASE_INVALIDATION_INTERFACE_H_
-
-#include <stdint.h>
-
-#include <string>
-
-#include "sync/base/sync_export.h"
-
-namespace syncer {
-
-// An interface that wraps sync's interactions with the component that provides
-// it with invalidations.
-class SYNC_EXPORT InvalidationInterface {
- public:
-  // Orders invalidations based on version number and IsUnknownVersion().
-  static bool LessThanByVersion(const InvalidationInterface& a,
-                                const InvalidationInterface& b);
-
-  InvalidationInterface();
-  virtual ~InvalidationInterface();
-
-  // Returns true if this is an 'unknown version' invalidation.
-  // Such invalidations have no valid payload or version number.
-  virtual bool IsUnknownVersion() const = 0;
-
-  // Returns the payload of this item.
-  // DCHECKs if this is an unknown version invalidation.
-  virtual const std::string& GetPayload() const = 0;
-
-  // Retursn the version of this item.
-  // DCHECKs if this is an unknown version invalidation.
-  //
-  // It is preferable to use the LessThan() function, which handles unknown
-  // versions properly, rather than this function.
-  virtual int64_t GetVersion() const = 0;
-
-  // This function will be called when the invalidation has been handled
-  // successfully.
-  virtual void Acknowledge() = 0;
-
-  // This function should be called if a lack of buffer space required that we
-  // drop this invalidation.
-  //
-  // To indicate recovery from a drop event, the receiver of this invalidation
-  // will call Acknowledge() on the most recently dropped invalidation.
-  virtual void Drop() = 0;
-};
-
-}  // namespace syncer
-
-#endif  // SYNC_INTERNAL_API_PUBLIC_BASE_INVALIDATION_INTERFACE_H_