Issue description:
Chrome Remote Desktop is not establishing connection if a Mac computer is involved, either if you want to access the Mac from another computer, or manage another computer from Mac. Any attempt to connect will end up in the error message 'Unable to reach the host. This is probably due to the configuration of the network you're using'. 

Steps to reproduce the problem:
1. Download CRD on your Mac.
2. Run CRD and either attempt to access or share.
3. Wait for connection to be established.
3. Session will fail either by giving a network host error or not loading after several minutes, hours, days.

What is the expected behavior?
CRD should connect after a couple of seconds after the code is entered.

What went wrong?
CRD doesn't connect.

Did this work before?
Yes.

Any other comments?
- This seems to be affecting Mac devices only where a connection will go from Mac to Mac/Linux/Windows/ChromeOS, and vice-versa. It works fine if Mac is not involved.

Tested under the following environments

Chrome Browser Version 51.0.2704.106 (64-bit)
Chrome Remote Desktop extension 51.0.2704.53 and 52.0.2743.48.
Chrome Remote Desktop host 51.0.2704.7
MAC OS 10.11.3 (both laptops) Also Windows 7 SP2 64-bit and Windows 10. It may affect this specific OSX version.

Chrome Connectivity Diagnostics reports no network issues, tested both Ethernet and Wireless, managed networks, and fully open and public ones with the same result.