Optional Permissions

Introduction

You can use the chrome.permissions API to request declared optional permissions at run time rather than install time, so users understand why the permissions are needed and grant only those that are necessary.

Step 1: Decide which permissions are required and which are optional

An extension can declare both required and optional permissions. In general, you should:

• Use required permissions when they are needed for your extension’s basic functionality.
• Use optional permissions when they are needed for optional features in your extension.

Advantages of required permissions:

• Fewer prompts: An extension can prompt the user once to accept all permissions.
• Simpler development: Required permissions are guaranteed to be present.

Advantages of optional permissions:

• Better security: Extensions run with fewer permissions since users only enable permissions that are needed.
• Better information for users: An extension can explain why it needs a particular permission when the user enables the relevant feature.
• Easier upgrades: When you upgrade your extension, Opera will not disable it for your users if the upgrade adds optional rather than required permissions.

Step 2: Declare optional permissions in the manifest

Declare optional permissions in your extension manifest with the optional_permissions key, using the same format as the permissions field:

{
	"name": "My extension",
	"optional_permissions": [
		"tabs",
		"http://www.example.com/"
	]
}

You can specify any of the following as optional permissions:

• host permissions
• background
• bookmarks
• clipboardRead
• clipboardWrite
• contentSettings
• contextMenus
• cookies
• debugger
• history
• idle
• management
• notifications
• pageCapture
• tabs
• topSites
• webNavigation
• webRequest
• webRequestBlocking

Step 3: Request optional permissions

Request the permissions from within a user gesture using permissions.request():

document.querySelector('#my-button').addEventListener('click', function (event) {
	// Permissions must be requested from inside a user gesture,
	// like a button’s click handler.
	chrome.permissions.request({
		permissions: ['tabs'],
		origins: ['http://www.example.com/']
	}, function (granted) {
		// The callback argument will be true
		// if the user granted the permissions.
		if (granted) {
			doSomething();
		} else {
			doSomethingElse();
		}
	});
});

Opera prompts the user if adding the permissions results in different warning messages than the user has already seen and accepted.

Step 4: Check the extension’s current permissions

To check whether your extension has a specific permission or set of permissions, use permission.contains():

chrome.permissions.contains({
	permissions: ['tabs'],
	origins: ['http://www.google.com/']
}, function (result) {
	if (result) {
		// The extension has the permissions.
	} else {
		// The extension doesn't have the permissions.
	}
});

Step 5: Remove the permissions

You should remove permissions when you no longer need them. After a permission has been removed, calling permissions.request() usually adds the permission back without prompting the user.

chrome.permissions.remove({
	permissions: ['tabs'],
	origins: ['http://www.google.com/']
}, function (removed) {
	if (removed) {
		// The permissions have been removed.
	} else {
		// The permissions have not been removed
		// (e.g., you tried to remove required permissions).
	}
});