ViewAttachmentManager

Manages a FrameLayout that is attached directly to a WindowManager that other views can be added and removed from.

To render a View, the View must be attached to a WindowManager so that it can be properly drawn. This class encapsulates a FrameLayout that is attached to a WindowManager that other views can be added to as children. This allows us to safely and correctly draw the View associated with ViewRenderable's while keeping them isolated from the rest of the activities View hierarchy.

Additionally, this manages the lifecycle of the window to help ensure that the window is added/removed from the WindowManager at the appropriate times.