Chrome OS beta 64 includes an option to run multiple Android apps in parallel on a Chromebook without pausing when the user has another app running. The option makes multitasking on a Chromebook considerably easier in practice.
The feature is in Chrome OS 64, but is not enabled by default. Users must activate Developer Options by tapping the Build Number several times in About Device, in the Android options. Then they can enable parallel running of tasks at the bottom of the Developer Options menu. Then an Android app will continue to run regardless of where the user directs their interactions next.
The feature is included in the latest beta of Chrome OS and users can switch to it by switching to the beta channel in Chrome OS options. In doing so, users will not lose their data, but if they want to go back from beta to stable, they will lose their data. The new feature was discovered by Chrome Unboxed, who immediately made a video demonstration of it.
Chrome OS has had updates before for multitasking. There is also the option to split the screen neatly into two parts and to place two apps in the halves. That function is still experimental.