Material: Hamburger Menu and Navigation

We're currently thinking about our hamburger menu and the navigation in our app. Here's an example using the Drive app:

This is the Drive app when opening it from the launcher.

This is the menu, now I tap on Starred

This is the Starred screen. Note the hamburger menu icon on the top left. What would be the expected navigation now, when pressing the Android hardware back button? The Drive app goes back to the My Drive page as shown in the first image. But one could also argue that the app closes since the My Drive page is not a root view, and the Starred screen does not have a back button.

What would be the preferred way of handling this? It seems that most apps we checked are pretty inconsistent on this topic.