On Wednesday, Google Drive started integrating with Yahoo Mail and WhatsApp. Drive already has integrated with several third-party apps before. Yahoo Mail has gained an interface which allows you to search for the Drive-hosted file you require and also grant editing or viewing privileges to its recipients. WhatsApp has a new button in conversations which let you attach Drive docs to messages.
The process is much easier than before when users would have to paste a hyperlink or download the document and manually attach it to a message. The integration will be seen in a week or 2.