[GStreamer] change network state to idle when delaying the load

https://bugs.webkit.org/show_bug.cgi?id=305473

Reviewed by Xabier Rodriguez-Calvar.

Sometimes applications create a <video> tag with 'preload="none"' and
then remove the element from the DOM without ever starting playback.
This results in the video element being leaked, because
HTMLMediaElement::virtualHasPendingActivity() retains the element while
its network state is still "Loading".

See: #1594

This patch keeps the default behaviour of changing the NetworkState to
"Loading", except in the case of a delayed load (the case triggered by
preload="none"), in which it's set to Idle and therefore allowing the
full destruction of the video element.

Original author: Eugene Mutavchi <Ievgen_Mutavchi@comcast.com>

* Source/WebCore/platform/graphics/gstreamer/MediaPlayerPrivateGStreamer.cpp:
(WebCore::MediaPlayerPrivateGStreamer::load): Reset NetworkState to Idle in case of delayed load. Set to Loading otherwise.

Canonical link: https://commits.webkit.org/305578@main

Author: emutavchi

Source/WebCore/platform/graphics/gstreamer/MediaPlayerPrivateGStreamer.cpp

@@ -407,7 +407,7 @@ void MediaPlayerPrivateGStreamer::load(const String& urlString)
 
     // Reset network and ready states. Those will be set properly once
     // the pipeline pre-rolled.
-    m_networkState = MediaPlayer::NetworkState::Loading;
+    m_networkState = m_isDelayingLoad ? MediaPlayer::NetworkState::Idle : MediaPlayer::NetworkState::Loading;
     player->networkStateChanged();
     m_readyState = MediaPlayer::ReadyState::HaveNothing;
     player->readyStateChanged();