sync: Add non-blocking type encryption (retry)

sync/engine/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_ENTITY_TRACKER_H_
 #define SYNC_ENGINE_ENTITY_TRACKER_H_
 
 #include <string>
 
 #include "base/basictypes.h"
+#include "base/memory/scoped_ptr.h"
 #include "base/time/time.h"
 #include "sync/base/sync_export.h"
+#include "sync/internal_api/public/non_blocking_sync_common.h"
 #include "sync/protocol/sync.pb.h"
 
 namespace syncer {
 
 // Manages the pending commit and update state for an entity on the sync
 // thread.
 //
 // It should be considered a helper class internal to the
 // ModelTypeSyncWorker.
 //
@@ skipping 51 matching lines @@
   // 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 response_version,
                              int64 sequence_number);
 
   // Handles receipt of an update from the server.
   void ReceiveUpdate(int64 version);
 
+  // Handles the receipt of an pending 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+  // is out of date.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 ReceivePendingUpdate(const UpdateResponseData& data);
+
+  // Functions to fetch the latest pending update.
+  bool HasPendingUpdate() const;
+  UpdateResponseData GetPendingUpdate() const;
+
+  // Clears the pending update.  Allows us to resume regular commit behavior.
+  void ClearPendingUpdate();
+
  private:
   // Initializes received update state.  Does not initialize state related to
   // pending commits and sets |is_commit_pending_| to false.
   EntityTracker(const std::string& id,
                 const std::string& client_tag_hash,
                 int64 highest_commit_response_version,
                 int64 highest_gu_response_version);
 
   // Initializes all fields.  Sets |is_commit_pending_| to true.
   EntityTracker(const std::string& id,
@@ skipping 45 matching lines @@
   // The following fields are valid only when a commit is pending.
   // This is where we store the data that is to be sent up to the server
   // at the next possible opportunity.
   int64 base_version_;
   base::Time ctime_;
   base::Time mtime_;
   std::string non_unique_name_;
   bool deleted_;
   sync_pb::EntitySpecifics specifics_;
 
+  // An update for this item 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 we can't decrypt right now.
+  scoped_ptr<UpdateResponseData> pending_update_;
+
   DISALLOW_COPY_AND_ASSIGN(EntityTracker);
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_ENGINE_ENTITY_TRACKER_H_