Summary:
This diff adds a new variable called "DisplayMode" into SurfaceHandler.cpp and FacebookAppRouteHandler.js. The purpose of DisplayMode is for the native pre-render system to notify React that the a surface is either being "pre-rendered" or "rendered"
When the surface is being "pre-rendered" (displayMode == "SUSPENDED"), react will create and commit React Trees, but it will not execute use-effect callbacks
When the surface is being "rendered" (displayMode == "VISIBLE"), react will create and commit React Trees and it will not execute all use-effect callbacks that weren't executed during "pre-rendering"
By default surfaces are going to be rendered with displayMode == "VISIBLE".
This diff should not create any change of behavior for now, this is the infra required to integrate the new offScreen API the react team is working on for pre-rendering system
changelog: [internal] internal
Reviewed By: yungsters
Differential Revision: D27614664
fbshipit-source-id: f1f42fdf174c2ffa74174feb1873f1d5d46e7a95