Reflector 3 supports native connections from Chromebook, but for more control, you can also use AirParrot for Chrome OS.
This article explains how to mirror a Chromebook screen to Reflector 3 without using AirParrot for Chrome OS.
To mirror your Chromebook screen to a computer running Reflector 3:
Click the control menu in the bottom right corner of your Chromebook screen (near the clock
Select “Cast devices available” to see a list of all Reflector-enabled computers that are available
Select the computer that you would like to mirror your Chromebook display to
Then select “Internal Display” from the Google Cast window
Your entire Chromebook display is now wirelessly mirrored to your Reflector-enabled computer