def update_cache(cache)
      client = GData::Client::Contacts.new
      client.clientlogin(@user, @pw)

      # Retrieve changes updating cache until no more changes.
      idx = 1
      orig_last_modified = cache.cache_last_modified
      until load_chunk(client, idx, cache, orig_last_modified) < @fetch_size
        idx += @fetch_size
      end

      # Write cache to disk
      cache.save
    end
def update_cache(cache)
      client = GData::Client::Contacts.new
      client.clientlogin(@user, @pw)

      # Retrieve changes updating cache until no more changes.
      idx = 1
      orig_last_modified = cache.cache_last_modified
      until load_chunk(client, idx, cache, orig_last_modified) < @fetch_size
        idx += @fetch_size
      end

      # Write cache to disk
      cache.save
    end
Ctor.

 @param [String] user Login to use to connect to GMail.
 @param [String] pw Password to use to connect to GMail.
 @param [Integer] fetch_size Number of records to retrieve at a time.
 Refresh the passed <tt>ContactsCache</tt> with the latest contact
 changes/deletions from Gmail.

 @param [Bitsa::ContacstCache] cache Cache to be updated from GMail.

 @return [nil]