The reason is that gcm network channel is sending requests to production servers using access token obtained from testgaia. This token does not get accepted on server and request is rejected.

Link to the implementation: https://code.google.com/p/chromium/codesearch#chromium/src/components/invalidation/impl/gcm_network_channel.cc&type=cs&sq=package:chromium&l=358&rcl=1463411924

The fix for this issue is either to provide commandline parameter to control invalidations url or to use GCM connection as transport for upstream invalidation messages. Later is one of our lower priority OKRs. 

This is in a way blocking the testgaia testing. Workaround is to manually trigger sync to make sure sync is working actually. 
Can you provide the commandline parameter so that I can use it until the actual issue is fixed?

Would using the GCM connection for upstreaming invalidation messages work? Or is there a different server to connect to than MCS as well?

I spoke with Kevin, he sais that testgaia instance is not currently setup to publish notifications, additional changes on server are needed to achieve this. This means that adding commandline parameter or switching upstream messages to GCM won't be enough to fix the issue.

This issue has been Available for over a year. If it's no longer important or seems unlikely to be fixed, please consider closing it out. If it is important, please re-triage the issue.

Sorry for the inconvenience if the bug really should have been left as Available. If you change it back, also remove the "Hotlist-Recharge-Cold" label.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot