sendMessage from extension background or popup to content script doesn’t work
In your background page you should call chrome.tabs.query({active: true, currentWindow: true}, function(tabs){ chrome.tabs.sendMessage(tabs[0].id, {action: “open_dialog_box”}, function(response) {}); }); instead of using chrome.extension.sendMessage as you currently do. The chrome.tabs variant sends messages to content scripts, whereas the chrome.extension function sends messages to all other extension components.