Use FeaturePolicy to implement iframe[allowfullscreen]
The previous CL (https://crrev.com/719a425c) tried to handle this in fullscreenIsSupported(), which misses the important case where the Feature Policy API is enabled, but the site uses 'allowfullscreen' iframe attributes.
This CL roughly mimics the intended behaviour of feature-policy allowfullscreen, by allowing access to fullscreen in same-origin iframes, and in cross-origin iframes where either a Feature-Policy header or an 'allowfullscreen' attribute is used, and the parent frame allows fullscreen.
BUG=666761
Review-Url: https://codereview.chromium.org/2585363002
Cr-Commit-Position: refs/heads/master@{#446393}
(cherry picked from commit 39d97d6645829da8b4c402b3112c81ebbe53004d)
Review-Url: https://codereview.chromium.org/2662443004 .
Cr-Commit-Position: refs/branch-heads/2987@{#152}
Cr-Branched-From: ad51088c0e8776e8dcd963dbe752c4035ba6dab6-refs/heads/master@{#444943}
6 files changed