I am not able to understand the term "off-screen-rendering" in the context of chromium embedded framework.
When should it used or How should it used.
It is very deep in the codebase(cef) to trace and find some meaning.
Please help.
You can see description here: GeneralUsage#Off-Screen Rendering
It can be used for, e.g., loading very big page in background and then displaying it (it will be much more faster).
Or, for example, for crawling pages full of js-code: CEF will run all scripts in background and return you the resulting page.