Download Fast Mobile Depth of Field FREE Unity. 

Note that effect works with the special custom shaders in the package listed below. It can work with your custom shaders only if you add depth to your shader

Fast Mobile Depth of Field consists of shaders for applying the depth of field to the scene. This approach is among the fastest in the market. During development the main goal was to maximally optimize the well-known depth of field technique, keeping the quality of the final image. The shader was tested on the low-end mobile device in a loaded scene.

SHADERS