HOTFIX 2014.4 - Custom Label Attributes for Google Product Feed.

Five custom fields (custom_label_0 to cusom_label_4) were added to google's product feed. 

Google is replacing regular Product Listing Ads campaigns with shopping campaigns. The "AdWords Labels" and "AdWords Grouping" attributes aren't supported in shopping campaigns.
For more information: https://support.google.com/adwords/answer/4637089,https://support.google.com/merchants/answer/188494