Search entry: center content when unfocused

The search entry looks a little off balance when it's empty (which is most of the time), because it's at the center of the screen, but the placeholder text and icon are left-aligned, leaving the rest of the entry empty.

It would be nicer if we could center the icon and placeholder text when the entry isn't active, and animate them to the left when someone focuses the entry or starts typing. It would look something like this: