Paint API should be available for same-origin frames but not to cross-origin/sandboxed frames.

On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".


PASS receivedEvent.source is document.getElementById('nonSandboxed').contentWindow
PASS receivedEntry.name is 'first-contentful-paint'
PASS didReceiveMessageFromSandboxedIframe is false
PASS Array.isArray(nonSandboxSupportedTypes) is true
PASS Array.isArray(sandboxSupportedTypes) is true
PASS didReceiveMessage is true
PASS nonSandboxSupportedTypes.includes("paint") is true
PASS sandboxSupportedTypes.includes("paint") is false
PASS PerformanceObserver first-contentful-paint callback was fired for same-origin frame but not for cross-origin frame
PASS successfullyParsed is true

TEST COMPLETE


TEXT