Revert of Remove the allowfullscreen exemption for the video-specific fullscreen API

Revert of Remove the allowfullscreen exemption for the video-specific fullscreen API (patchset #4 id:60001 of https://codereview.chromium.org/1058783006/)

Feedback from Vimeo on blink-dev asking for more time:
https://groups.google.com/a/chromium.org/d/msg/blink-dev/3NukIuOaU4c/MPyuWoDaz8AJ

New plan for removing the allowfullscreen exemption:
https://groups.google.com/a/chromium.org/d/msg/blink-dev/3NukIuOaU4c/LWeJeKYvf1MJ

Original issue's description:
> Remove the allowfullscreen exemption for the video-specific fullscreen API
> 
> Intent to Remove:
> https://groups.google.com/a/chromium.org/d/msg/blink-dev/3NukIuOaU4c/Boab2WxzhBYJ
> 
> Prompted by a question from Ali Alabbas (Microsoft) on blink-dev:
> https://groups.google.com/a/chromium.org/d/msg/blink-dev/f-V2GWatXkA/nvdHJ3xihMkJ
> 
> TEST=LayoutTests/media/video-controls-fullscreen-iframe.html
> 
> This test ensures that the allowfullscreen attribute is still not
> required for <video controls>, even though it is for the API call.
> 
> BUG=346236
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=194106

R=falken@chromium.org
BUG=496637
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=196661

[philipj_slow, 2015-06-03 22:51:08]

Created Revert of Remove the allowfullscreen exemption for the video-specific
fullscreen API

[falken, 2015-06-04 00:29:14]

Hey Philip, can you help me understand Vimeo's issue? I'm hoping we still have a
way forward to reland this change, as Microsoft also was interested in our plans
here.

Reading the blink-dev thread, some Vimeo embedders remove fullscreenallowed. I
gather this is OK as long as the allowfullscreen exemption exists. Do they mean
that for browsers without this exemption (i.e., non-WebKit/Blink ones), they
have a way to detect when <video> can't go HTML fullscreen and in this case they
fall back to some older API that allows them to? But in Blink ToT, they don't
have a way to feature detect, so they won't be able to do the fallback... but
nevertheless in the future Blink plans to remove the fallback?

Sorry for the naive questions!

[philipj_slow, 2015-06-04 08:39:17]

On 2015/06/04 00:29:14, falken wrote:
> Hey Philip, can you help me understand Vimeo's issue? I'm hoping we still have
a
> way forward to reland this change, as Microsoft also was interested in our
plans
> here.
> 
> Reading the blink-dev thread, some Vimeo embedders remove fullscreenallowed. I
> gather this is OK as long as the allowfullscreen exemption exists. Do they
mean
> that for browsers without this exemption (i.e., non-WebKit/Blink ones), they
> have a way to detect when <video> can't go HTML fullscreen and in this case
they
> fall back to some older API that allows them to? But in Blink ToT, they don't
> have a way to feature detect, so they won't be able to do the fallback... but
> nevertheless in the future Blink plans to remove the fallback?
> 
> Sorry for the naive questions!

Not naive at all!

I think it was a mistake to just remove the exemption for the web-facing API but
keep it for <video controls>, and it's bad that webkitSupportsFullscreen doesn't
reflect the change, making it impossible to feature detect that the restriction
applies.

I'm going to prepare a CL (based on this one) that gets rid of the exemption for
all cases and also adjusts webkitSupportsFullscreen. I'll ask you to take a
look, and if you think it makes sense revert this and merge to M44, then go with
the full removal in M45. That would involve a new Intent to Deprecate and Remove
on blink-dev, and possibly we could throw in a release cycle of deprecation as
well.

[philipj_slow, 2015-06-04 11:44:52]

OK, PTAL, the description links to the new plan on blink-dev. If you think that
makes sense I'd like to land this revert to get it into M44 as soon as possible,
even if the rest of the plan could change somewhat.

[philipj_slow, 2015-06-04 12:10:04]

The CQ bit was checked by philipj@opera.com to run a CQ dry run

[commit-bot: I haz the power, 2015-06-04 12:10:11]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1159593006/200001

[commit-bot: I haz the power, 2015-06-04 13:55:00]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-06-04 13:55:01]

Dry run: This issue passed the CQ dry run.

[philipj_slow, 2015-06-05 13:44:20]

philipj@opera.com changed reviewers:
+ jochen@chromium.org

[philipj_slow, 2015-06-05 13:44:21]

Jochen, can you PTAL? No reaction on blink-dev, but getting this revert into M44
soon would be a good thing.

[falken, 2015-06-08 03:06:41]

lgtm. Based on Vimeo feedback, sounds right to at least postpone this.

[jochen (gone - plz use gerrit), 2015-06-08 04:55:30]

lgtm

[philipj_slow, 2015-06-08 08:16:32]

The CQ bit was checked by philipj@opera.com

[commit-bot: I haz the power, 2015-06-08 08:16:53]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1159593006/200001

[commit-bot: I haz the power, 2015-06-08 09:38:10]

Committed patchset #2 (id:200001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=196661