The new Google Play website has switched to Web-P Images for icons and other graphics - so you are likely to encounter this file fomrat more prominently. If you want to use it in Photoshop you need a plugin. I tried a couple of them and only one works fine with transparencies. You can download it for free on GitHub from Brendan Bolles. Get it here : https://github.com/fnordware/AdobeWebM

BTW: You don't put this plugin in the general plugin folder but in Adobe Photoshop CS6 (64 Bit)/Required/Plug-Ins/File Formats