Implement a bag of chips for sync.

sync/syncable/directory.h

Index: sync/syncable/directory.h
diff --git a/sync/syncable/directory.h b/sync/syncable/directory.h
index b34882feb40ee319598b8832109ccc05e4704478..27e1d1e0379b3ec3ae129634056b750ebc579d91 100644
--- a/sync/syncable/directory.h
+++ b/sync/syncable/directory.h
@@ -170,6 +170,9 @@ class Directory {
     int64 next_id;
     // The persisted notification state.
     std::string notification_state;
+    // The serialized bag of chips we were given by the server. Contents are
+    // opaque to the client.

[Nicolas Zea, 2012/09/07 18:38:43]

Mention the ChipBag message defined in sync.proto

[qsr, 2012/09/10 08:12:37]

Done.

+    std::string bag_of_chips;
   };
 
   // What the Directory needs on initialization to create itself and its Kernel.
@@ -260,6 +263,11 @@ class Directory {
   std::string store_birthday() const;
   void set_store_birthday(const std::string& store_birthday);
 
+  // (Account) Bag of chip is an opaque state used by the server to track the
+  // client.
+  std::string bag_of_chips() const;
+  void set_bag_of_chips(const std::string& bag_of_chips);
+
   std::string GetNotificationState() const;
   void SetNotificationState(const std::string& notification_state);