sync: Inject sync/'s dependency on invalidations

sync/internal_api/public/base/invalidation.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 SYNC_INTERNAL_API_PUBLIC_BASE_INVALIDATION_H_
 #define SYNC_INTERNAL_API_PUBLIC_BASE_INVALIDATION_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 66 matching lines @@
   // re-deliver this invalidation in the event of a crash or restart.
   void Acknowledge() const;
 
   // Informs the ack tracker that this invalidation will not be serviced.
   //
   // If a client's buffer reaches its limit and it is forced to start dropping
   // invalidations, it should call this function before dropping its
   // invalidations in order to allow the ack tracker to drop the invalidation,
   // too.
   //
-  // The drop record will be tracked by the specified
-  // DroppedInvalidationTracker.  The caller should hang on to this tracker.  It
-  // will need to use it when it recovers from this drop event, or if it needs
-  // to record another drop event for the same ObjectID.  Refer to the
-  // documentation of DroppedInvalidationTracker for more details.
-  void Drop(DroppedInvalidationTracker* tracker) const;
+  // To indicate recovery from a drop event, the client should call
+  // Acknowledge() on the most recently dropped inavlidation.
+  void Drop();
 
   scoped_ptr<base::DictionaryValue> ToValue() const;
   std::string ToString() const;
 
  private:
   Invalidation(const invalidation::ObjectId& id,
                bool is_unknown_version,
                int64 version,
                const std::string& payload,
                AckHandle ack_handle);
@@ skipping 13 matching lines @@
   std::string payload_;
 
   // A locally generated unique ID used to manage local acknowledgements.
   AckHandle ack_handle_;
   syncer::WeakHandle<AckHandler> ack_handler_;
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_INTERNAL_API_PUBLIC_BASE_INVALIDATION_H_