This is the OAuth 2.0 library for Chrome Extensions. It's available on both github and on google code.

Sample extensions that use this library can be found in this same distribution, but please note that you will need to run the cp-oauth2.sh script inside the samples directory to get these samples to work.

How to use this library

Register your application with an OAuth 2.0 endpoint that you'd like to use. If it's a Google API you're calling, go to the Google APIs page, create your application and note your client ID and client secret. For more info on this, check out the Google OAuth 2.0 docs. When you setup your application, you will be asked to provide redirect URI(s). Please provide the URI that corresponds to the service you're using.

Here's a table that will come in handy:

Adapter	Redirect URI	Access Token URI
google	http://www.google.com/robots.txt	https://accounts.google.com/o/oauth2/token
facebook	http://www.facebook.com/robots.txt	https://graph.facebook.com/oauth/access_token
github	https://github.com/robots.txt	https://github.com/login/oauth/access_token

Step 1: Copy library

You will need to copy the oauth2 library into your chrome extension root into a directory called oauth2.

Step 2: Inject content script

Then you need to modify your manifest.json file to include a content script at the redirect URL used by the Google adapter. The "matches" redirect URI can be looked up in the table above:

"content_scripts": [
  {
    "matches": ["http://www.google.com/robots.txt*"],
    "js": ["oauth2/oauth2_inject.js"],
    "run_at": "document_start"
  }
],

Step 3: Allow access token URL

Also, you will need to add a permission to Google's access token granting URL, since the library will do an XHR against it. The access token URI can be looked up in the table above as well.

"permissions": [
  "https://accounts.google.com/o/oauth2/token"
]

Step 4: Include the OAuth 2.0 library

Next, in your extension's code, you should include the OAuth 2.0 library:

<script src="/oauth2/oauth2.js"></script>

Step 5: Configure the OAuth 2.0 endpoint

And configure your OAuth 2 connection by providing clientId, clientSecret and apiScopes from the registration page. The authorize() method may create a new popup window for the user to grant your extension access to the OAuth2 endpoint.

var googleAuth = new OAuth2('google', {
  client_id: '17755888930840',
  client_secret: 'b4a5741bd3d6de6ac591c7b0e279c9f',
  api_scope: 'https://www.googleapis.com/auth/tasks'
});

googleAuth.authorize(function() {
  // Ready for action, can now make requests with
  googleAuth.getAccessToken()
});

Step 6: Use the access token

Now that your user has an access token via auth.getAccessToken(), you can request protected data by adding the accessToken as a request header

xhr.setRequestHeader('Authorization', 'OAuth ' + myAuth.getAccessToken())

or by passing it as part of the URL (depending on your particular impl):

myUrl + '?oauth_token=' + myAuth.getAccessToken();

Note: if you have multiple OAuth 2.0 endpoints that you would like to authorize with, you can do that too! Just inject content scripts and add permissions for all of the providers you would like to authorize with.

For more information about this library, please see this blog post.