Bug 252938 – ManagedMediaSource content should be evicted whenever it is under memory pressure

• Component: Media
• Status: RESOLVED FIXED

[Jean-Yves Avenard [:jya]]

Right now, the decision to act on a media element following a memory pressure event is left to the WebProcess' MemoryPressureHandler which is set in `WebProcess::initializeWebProcess`
which ends up calling `releaseCriticalMemory` [1]
through the loop:
```
#if ENABLE(VIDEO)
    for (auto* mediaElement : HTMLMediaElement::allMediaElements()) {
        if (mediaElement->paused())
            mediaElement->purgeBufferedDataIfPossible();
    }
#endif
```

The eviction of data in a ManagedMediaSource is designed to allow the media element to continue being playable, we do not have to wait for it to be paused.

And it should be up to the MediaElement itself to determine of data should be purged or not anyway.

[1] https://searchfox.org/wubkat/source/Source/WebCore/page/MemoryRelease.cpp#118-123

[Radar WebKit Bug Importer]

<rdar://problem/105908445>

[Jean-Yves Avenard [:jya]]

Pull request: https://github.com/WebKit/WebKit/pull/10708

[EWS]

Committed 260871@main (fee371950f62): <https://commits.webkit.org/260871@main>

Reviewed commits have been landed. Closing PR #10708 and removing active labels.

[Ryan Haddad]

This change caused TestWebKitAPI.WebKit.MediaBufferingPolicy to consistently fail on macOS bots:

    TestWebKitAPI.WebKit.MediaBufferingPolicy
        
        /Volumes/Data/worker/Apple-Ventura-Release-Build/build/Tools/TestWebKitAPI/Tests/WebKitCocoa/MediaBufferingPolicy.mm:47
        Expected equality of these values:
          expected
            Which is: "PurgeResources"
          observed
            Which is: "LimitReadAhead"


https://build.webkit.org/#/builders/702/builds/1684/steps/19/logs/stdio

https://results.webkit.org/?suite=api-tests&test=TestWebKitAPI.WebKit.MediaBufferingPolicy

[WebKit Commit Bot]

Re-opened since this is blocked by bug 253004

[Jean-Yves Avenard [:jya]]

Pull request: https://github.com/WebKit/WebKit/pull/10774

[EWS]

Committed 260920@main (98b2a211bb53): <https://commits.webkit.org/260920@main>

Reviewed commits have been landed. Closing PR #10774 and removing active labels.