The chrome.extension module has utilities that can be used by any extension page. It includes support for exchanging messages between an extension and its content scripts or between extensions, as described in detail in Message Passing.

Support for content scripts

Unlike the other chrome.* APIs, parts of chrome.extension can be used by content scripts:

sendRequest() and onRequest

Simple communication with extension pages

connect() and onConnect

Extended communication with extension pages

getURL()

Access to extension resources such as image files

For details, see Content Scripts.