Consider injecting LegacyBar into layout in Base Activities

[Cheesebaron]

Instead of having to explicitly specify the Bar in the Layout, somehow inject it into the Layout when using the Base Activities.

@jamesmontemagno what do you think of this?

[jamesmontemagno]

Hmmm yeah I do like this idea with the option to hide it so people can make a "full screen" app.

I think it would make it nice and then they could just apply the theme attributes to the overall theme of the app which would be nice.

[Cheesebaron]

Overriding SetContentView could probably enable us doing this pretty easily.