Hi, Pratibha,
Can you please share some details about the error that your are getting when calling register? It should be much easier to understand the problem on your windows 7 system them.
Also, if you visit chrome://gcm-internals from the profile that your are trying to run your extension you will get some extra information about the status of GCM. You want to make sure that Connection status is connected and that Android ID is set (should start with 0x4). You can share these values with me directly. Please don't share them publicly to the group.
If you are not seeing anything in that table, it might be that your GCM store is corrupted. You can either delete the profile and start over, or go into the profile folder and delete GCM Store folder. (Older versions of Chrome are not able to recover from store corruption by itself.)
Please reach out to me if you still have problems and I'll gladly assist you.
Regards.
Filip Gorski