See http://www.chromium.org/blink#launch-process for an overview of the
Blink launch process.

This launch issue is used for standards and implementation tracking only,
not for Chrome approval regarding privacy, security, legal, UI, testing,
accessibility etc. If your feature requires approval in any of those areas
please additionally create a Type=Launch issue (note you will most likely
want a PM to guide you through the Type=Launch process, guidance can be
found at go/newchromefeature)

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Change description:
Require user gesture for sandboxed iframe w/ 'allow-top-navigation' to navigate top-level page, and the top-level navigation will be blocked if there is no user gesture. This change would enable more use cases of sandboxing untrusted third-party contents (eg., ads) by allowing top navigation while blocking malicious auto-redirecting, and thus help building a safer internet.

Changes to API surface:
Require a user gesture to navigate top-level page for sandboxed iframe w/ 'allow-top-navigation', and the top-level navigation will be blocked if it's not triggered by a user gesture.

Links:
Public standards discussion: https://github.com/WICG/interventions/issues/42

Support in other browsers:
Internet Explorer: not yet
Firefox: not yet
Safari: not yet

*Make sure to fill in any labels with a -?, including all OSes this change
affects. Feel free to leave other labels at the defaults.