Google have been introducing restrictions in add-in functionality recently.
Microsoft blogged about this here http://blogs.technet.com/b/office_integration__sharepoint/archive/2015/04/24/unable-to-open-sharepoint-documents-in-rich-client-from-chrome.aspx
A permanent fix has been introduced with the August 2015 CU
August 11, 2015, update for SharePoint Foundation 2013 (KB3055015) contains the following fix:
"Some client and SharePoint integrated functions do not work in Chrome that has the NPAPI plugins enabled. For example, the Create a workflow in SharePoint designer function does not work."
Shame about the regression bug in this CU that prevents users from adding attachments to list items L