bbc.co.uk: Video goes black with only audio playing when exiting PiP mode

[jyavenard]

ba39716

bbc.co.uk: Video goes black with only audio playing when exiting PiP mode
https://bugs.webkit.org/show_bug.cgi?id=257711
rdar://108304377

Reviewed by Jer Noble.

Only fire the fullscreen change event once we did enter fullscreen.
This gives time for the UI process to complete exiting PiP in the UI process.

The process for exiting PiP and go back into fullscreen is a complicated
(and unnecessary) dance between the content and the UI process.
didStopPictureInPicture (UI) -> requestRestoreFullScreen (CP) -> EnterFullScreen (UI)
 -> WillEnterFullscreen (CP) -> beganEnterFullScreen (UI) -> didEnterFullScreen (UI)
 -> didEnterFullScreen (CP)

Previously, the events `fullscreenchange` was fired in WillEnterFullscreen.
if a JS event listener was set, and attempted to exit PiP then (as BBC website is doing)
it would have left VideoFullscreenInterfaceAVKit in a broken state
once it received `beganEnterFullScreen` as it's not an handled chained of event.

By letting the UI process complete the exit of PiP back to fullscreen,
we can avoid the problem from occurring alltogether, and this is simply
done by firing the events and resolving the promise in didEnterFullScreen.

We limit this behaviour to BBC.com

This entire code is in serious need of a rewrite.

Manually tested under all possible interface scenarios:
- Entering PiP, Exiting PiP using BBC main player control.
- Entering PiP, Exiting PiP using PiP controller button.
- Entering fullscreen via BBC control, entering PiP using PiP button, exiting PiP using BBC main player control
- As above but using PiP controller button as last step.
- Going into Auto-Pip by swiping home and exiting PiP.
- Entering PiP, quitting PiP (X button)

* Source/WebCore/dom/FullscreenManager.cpp:
(WebCore::FullscreenManager::willEnterFullscreen):
(WebCore::FullscreenManager::didEnterFullscreen):
* Source/WebCore/page/Quirks.cpp:
(WebCore::Quirks::shouldDelayFullscreenEventWhenExitingPictureInPictureQuirk const):
* Source/WebCore/page/Quirks.h:

Canonical link: https://commits.webkit.org/264974@main

93cdf18

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 wincairo
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	🧪 api-mac	✅ 🛠 gtk
	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🧪 gtk-wk2
	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🧪 api-gtk
	✅ 🛠 tv	🧪 mac-AS-debug-wk2
	✅ 🛠 tv-sim
✅ 🛠 🧪 merge	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on previous version of this PR (hash 5ed1fd9)

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 wincairo
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	⏳ 🧪 api-mac	✅ 🛠 gtk
	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	❌ 🧪 gtk-wk2
	❌ 🧪 api-ios	❌ 🧪 mac-wk2	✅ 🧪 api-gtk
	✅ 🛠 tv	❌ 🧪 mac-AS-debug-wk2
	✅ 🛠 tv-sim
	✅ 🛠 watch
	✅ 🛠 watch-sim

[jernoble]

The problem with this change is it means the fullscreenchange event won't fire until after the transition into fullscreen has started. For sites that use that event to re-layout into a fullscreen mode, it will mean that transition will have flashes of the original layout visible to the user.

Perhaps we can limit this change to only the BBC with a quirk?

[webkit-early-warning-system]

EWS run on previous version of this PR (hash d1ebf7e)

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
❌ 🧪 style	❌ 🛠 ios	❌ 🛠 mac	❌ 🛠 wpe	⏳ 🛠 wincairo
❌ 🧪 bindings	❌ 🛠 ios-sim	❌ 🛠 mac-AS-debug	❌ 🧪 wpe-wk2
❌ 🧪 webkitperl	❌ 🧪 ios-wk2	❌ 🧪 api-mac	❌ 🛠 gtk
	❌ 🧪 ios-wk2-wpt	❌ 🧪 mac-wk1	❌ 🧪 gtk-wk2
⏳ 🛠 🧪 jsc	❌ 🧪 api-ios	❌ 🧪 mac-wk2	❌ 🧪 api-gtk
	❌ 🛠 tv	❌ 🧪 mac-AS-debug-wk2
	⏳ 🛠 tv-sim	❌ 🧪 mac-wk2-stress
	⏳ 🛠 watch
	❌ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on current version of this PR (hash 93cdf18)

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 wincairo
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	🧪 api-mac	✅ 🛠 gtk
	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🧪 gtk-wk2
	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🧪 api-gtk
	✅ 🛠 tv	🧪 mac-AS-debug-wk2
	✅ 🛠 tv-sim
✅ 🛠 🧪 merge	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-commit-queue]

Committed 264974@main (ba39716): https://commits.webkit.org/264974@main

Reviewed commits have been landed. Closing PR #14737 and removing active labels.