The Google Drive Android app is now gaining support for password-protected Microsoft Office files. Although Google has yet to make a main announcement detailing the change, the app has recently been updated on the Google Play Store which now lists the newly added support as part of the new update's changelog. As a result, Android device owners who often use the Google Drive app to access files will now have the added convenience of also being able to view password-protected files when they come through. As an extension of this, it now also seems highly likely this not only includes the option to fully open the files, but also to preview them before opening. With the update now showing as live on the Google Play Store, this does suggest the update is already en route to devices and so it's likely it has already arrived on some devices, bringing with it the new support.
Those more used to accessing documents through the web-based version of Google Drive will already be familiar with this feature as the ability to access these password-locked files became available on the web some time ago. Therefore, this latest update is not exactly introducing a new feature, but instead looks to bring the Android app experience up to date and in line with the web-based version. Speaking of the web-based version of Google Drive, this version only recently underwent a new makeover designed to add more Material Design elements with a view to also bringing it more in line with other Google-related services available via the web, including Gmail. The overall riding theme here is Google looking to harmonize the experience to its users, across its different services.
As for the rest of the Android app update, it does seem as though the new password-protected Office file support is the main attraction as the changelog does not specifically name-drop any other new features or improvements as included. That is, other than the "bug fixes and performance improvements" that are usually included with Google service and product updates like this. As mentioned, this update is already now understood to be on its way out to devices.