[Sync] USS: Ignore encryption changes during conflict resolution 2/2

sync/engine/worker_entity_tracker.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_ENGINE_WORKER_ENTITY_TRACKER_H_
 #define SYNC_ENGINE_WORKER_ENTITY_TRACKER_H_
 
 #include <stdint.h>
 
 #include <memory>
 #include <string>
 
 #include "base/macros.h"
 #include "base/time/time.h"
 #include "sync/base/sync_export.h"
 #include "sync/protocol/sync.pb.h"
 
 namespace syncer_v2 {
 struct CommitRequestData;
+struct CommitResponseData;
 struct UpdateResponseData;
 
 // Manages the pending commit and update state for an entity on the sync
 // thread.
 //
 // It should be considered a helper class internal to the
 // ModelTypeWorker.
 //
 // Maintains the state associated with a particular sync entity which is
 // necessary for decision-making on the sync thread.  It can track pending
 // commit state, received update state, and can detect conflicts.
 //
 // This object may contain state associated with a pending commit, pending
 // update, or both.
 class SYNC_EXPORT WorkerEntityTracker {
  public:
   // Initializes the entity tracker's main fields. Does not initialize state
   // related to a pending commit.
   WorkerEntityTracker(const std::string& id,
                       const std::string& client_tag_hash);
 
   ~WorkerEntityTracker();
 
   // Returns true if this entity should be commited to the server.
   bool HasPendingCommit() const;
 
-  // Populates a sync_pb::SyncEntity for a commit.  Also sets the
-  // |sequence_number|, so we can track it throughout the commit process.
-  void PopulateCommitProto(sync_pb::SyncEntity* commit_entity,
-                           int64_t* sequence_number) const;
+  // Populates a sync_pb::SyncEntity for a commit.
+  void PopulateCommitProto(sync_pb::SyncEntity* commit_entity) const;
 
   // Updates this entity with data from the latest version that the
   // model asked us to commit.  May clobber state related to the
   // model's previous commit attempt(s).
   void RequestCommit(const CommitRequestData& data);
 
   // Handles the receipt of a commit response.
   //
-  // Since commits happen entirely on the sync thread, we can safely assume
-  // that our item's state at the end of the commit is the same as it was at
-  // the start.
-  void ReceiveCommitResponse(const std::string& response_id,
-                             int64_t response_version,
-                             int64_t sequence_number);
+  // Since commits happen synchronously on the sync thread, our item's state
+  // at the end of the commit is the same as it was at the start, which is
+  // leveraged to let us fill some local-only data in on |ack|.

[skym, 2016/04/29 18:43:19]

This is phrased like an implementation/definition comment, not a declaration
comment. Why does this data need to be filled?

[maxbogue, 2016/05/03 17:46:15]

I moved the bulk of the comment to the implementation.

+  void ReceiveCommitResponse(CommitResponseData* ack);
 
   // Handles receipt of an update from the server.
   void ReceiveUpdate(int64_t version);
 
   // Handles the receipt of an encrypted update from the server.
   //
   // Returns true if the tracker decides this item is worth keeping.  Returns
   // false if the item is discarded, which could happen if the version number
   // is out of date.
   bool ReceiveEncryptedUpdate(const UpdateResponseData& data);
@@ skipping 34 matching lines @@
   // to do here is return it back to the model thread when the pending commit
   // is completed and confirmed.  Not valid if no commit is pending.
   int64_t sequence_number_;
 
   // The server version on which this item is based.
   int64_t base_version_;
 
   // A commit for this entity waiting for a sync cycle to be committed.
   std::unique_ptr<CommitRequestData> pending_commit_;
 
+  // The specifics hash for the pending commit if there is one, "" otherwise.
+  std::string pending_commit_specifics_hash_;
+
   // An update for this entity which can't be applied right now. The presence
   // of an pending update prevents commits.  As of this writing, the only
   // source of pending updates is updates that can't currently be decrypted.
   std::unique_ptr<UpdateResponseData> encrypted_update_;
 
   DISALLOW_COPY_AND_ASSIGN(WorkerEntityTracker);
 };
 
 }  // namespace syncer_v2
 
 #endif  // SYNC_ENGINE_WORKER_ENTITY_TRACKER_H_