Material Overlay Animation as per google guidlines http://www.google.co.in/design/spec/animation/meaningful-transitions.html
#Visual continuity "Transitioning between two visual states should be clear, smooth and effortless and not confuse the user. A well-designed transition does the heavy lifting and enables the user to clearly understand where their attention should be focused. A transition has three categories of elements: Incoming elements - whether newly generated or translated into the scene, these items need to be introduced or re-established. Outgoing elements - elements that are no longer relevant to the new context must be removed from the scene in an appropriate manner. Shared elements - elements that persist from the start to end of a transition. They can be as subtle as a single icon or become dominant as a gallery image grows to fit the screen."