Chrome is mentioned many times on that page:<p>&gt; Namespacing<p>&gt; At this time, all APIs are accessible through the chrome.* namespace. When we begin to add our own APIs, we expect to add them to the browser.* namespace. Developers will be able to use feature detection to determine if an API is available in browser.*.<p>&gt; See <a href="https:&#x2F;&#x2F;developer.chrome.com&#x2F;extensions&#x2F;manifest" rel="nofollow">https:&#x2F;&#x2F;developer.chrome.com&#x2F;extensions&#x2F;manifest</a> for a complete list of manifest directives. Of these, we currently support the following: