Gmail for Android Offers Combined Inbox View, Improved Search, and More
Android: If you’re tired of switching between your accounts just to see all your new email, Gmail has finally added a unified inbox view that displays all of your messages from all accounts in one place.
The All Inbox view consolidates email from all of your accounts, including IMAP accounts for other services (such as Yahoo or Outlook). These non-Gmail accounts also receive conversation threads just like Gmail, which is nice.
This update also features improved search autocomplete, more responsive animations, and a button to save attachments to Drive. We don’t see it on Google Play yet, most likely it is slowly spreading to all users.
All your mail in one place | Official Gmail Blog