Thanks for the reply. It's a function of letting users typing a non-English text without knowing the respective language's keyboard layout.
For example, if I want to type "வணக்கம்" in Tamil, but I don't know the keyboard layout for any Tamil font, I could still achieve the result (with transliteration enabled) by typing "vanakkam" and pressing space bar or the Enter key.
Google offers it for end-users, but there's no API to tap into. You could check how it works for any given language here: https://google.com/transliteration