Cofounder of Streak and helped write a lot of the InboxSDK. I can't give a definitive answer right now because we don't use Angular and thus don't have much experience with it. If you're able to specify a DOM node as the root of an Angular instance then you should be able to make it work.
If you try to make the top html tag as your root you'll probably run into a bad time particularly if other extensions make the same assumption. One major difference between writing an app for Gmail vs your own app is that multiple apps can and usually are running at the same time. This was one of the main motivations behind the SDK since many of our bug reports were a result from extension compatibility issues.
We do e2e testing with selenium/webdriver - so it's definitely doable. Tip for e2e testing is to pay for some extra Google Apps accounts so you can run your tests in parallel.
If you try to make the top html tag as your root you'll probably run into a bad time particularly if other extensions make the same assumption. One major difference between writing an app for Gmail vs your own app is that multiple apps can and usually are running at the same time. This was one of the main motivations behind the SDK since many of our bug reports were a result from extension compatibility issues.
We do e2e testing with selenium/webdriver - so it's definitely doable. Tip for e2e testing is to pay for some extra Google Apps accounts so you can run your tests in parallel.