迟迟等不到官方的更新通知，就自己下载ota档sideload update了
Android O brings picture-in-picture support so you can watch YouTube while
hailing a Lyft 这篇文中（https://goo.gl/21QGc1）有提到：
“Picture-in-picture is just one of the handful of new features that come with
Android O today. Compatible devices for the preview include the Nexus 5X,
Nexus 6P, Nexus Player, Pixel, Pixel XL, and Pixel C.”
在设定里头也有确定picture in picture有开启
https://imgur.com/joNzbEh
开了两个app来测试（hangouts, youtube）
想试验边用hangouts边用picture in picture 看youtube的情景
在切换的视窗没看到东西
https://imgur.com/KMoFNXE
在Youtube的视窗也是
https://imgur.com/6qgHs1B
试过单点、双点recent, home, back 都失败
有人有用nexus 5x 试成功吗？