How does chrome.browserAction work? - google-chrome

Question

Im trying to develop my first chrome extension and am running into an issue. Firstly I am using the following boilerplate as a page action:
http://extensionizr.com/!#{"modules":["browser-mode","with-persistent-bg","no-bg","with-custom-options","no-override","inject-css","inject-js","jquerymin"],"boolean_perms":["contentSettings","cookies","notifications"],"match_ptrns":[]}
In the inject.js, it downloads a list of urls from a remote server, checks the current url and if it matches it should do something. I was going to use a notification but I guess the notification comes from the current page and not the extension. So if you start the notification it will say "Do you want to enable notifications for amazon". Then I moved on to changing the icon. I would prefer doing both eventually. However, when I try and set text with the following:
chrome.browserAction.setIcon({path: 'icons/icon128-x.png'});
However, this is what I get in the console.
Uncaught TypeError: Cannot read property 'setIcon' of undefined
Any ideas?

Answer 1

you can't access chrome.browserAction in content.js, according to chrome extension document Content Scripts
Additionally, content script can access the following chrome APIs directly:
i18n
storage
runtime:
connect
getManifest
getURL
id
onConnect
onMessage
sendMessage
Content scripts are unable to access other APIs directly.

Answer 2

The extension manifest needs a "browser_action" section before the chrome.browserAction API is available to it:
Register your browser action in the extension manifest like this:
{
"name": "My extension",
...
"browser_action": {
"default_icon": { // optional
"19": "images/icon19.png", // optional
"38": "images/icon38.png" // optional
},
"default_title": "Google Mail", // optional; shown in tooltip
"default_popup": "popup.html" // optional
},
...
}
(From https://developer.chrome.com/extensions/browserAction#manifest.)