[GStreamer] Premature finishSeek in progressive video

https://bugs.webkit.org/show_bug.cgi?id=287568
Reviewed by Philippe Normand.

The MediaPlayerPrivateGStreamer::finishSeek() call is happening before
the GStreamer seek completes, causing the JavaScript webpage to see the
seek origin position on embedded systems with low CPU power (where seek
takes more time to complete). This has been reproduced on Raspberry Pi
using downstream wpe-2.38 and wpe-2.46, but I haven't been able to
reproduce it on the main branch on desktop with a powerful computer.
That doesn't mean that the problem isn't there.

See: #1456

MediaPlayerPrivateGStreamer::doSeek() calls updateBufferingStatus(),
which in turn calls updateStates(), which notifies the player of a
readyState change and HTMLMediaElement::setReadyState() calls
finishSeek().

This commit prevents the call to updateStates() from
updateBufferingStatus() in this particular case. This doesn't cause any
problem, since a new call to updateStates() will happen when the async
state change in the GStreamer pipeline completes.

* Source/WebCore/platform/graphics/gstreamer/MediaPlayerPrivateGStreamer.cpp:
(WebCore::MediaPlayerPrivateGStreamer::doSeek): Call updateBufferingStatus() with the shouldUpdateStates parameter set to false.
(WebCore::MediaPlayerPrivateGStreamer::updateBufferingStatus): Added shouldUpdateStates parameter (defaults to true).
* Source/WebCore/platform/graphics/gstreamer/MediaPlayerPrivateGStreamer.h: Added shouldUpdateStates parameter to updateBufferingStatus(), with a default value of true..

Canonical link: https://commits.webkit.org/290339@main

Author: eocanha

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

@@ -545,7 +545,7 @@ bool MediaPlayerPrivateGStreamer::doSeek(const MediaTime& position, float rate,
             quirksManager.resetBufferingPercentage(this, 0);
 
         // Make sure that m_isBuffering is set to true, so that when buffering completes it's set to false again and playback resumes.
-        updateBufferingStatus(GST_BUFFERING_STREAM, 0.0, true);
+        updateBufferingStatus(GST_BUFFERING_STREAM, 0.0, true, false);
         changePipelineState(GST_STATE_PAUSED);
     }
 
@@ -2214,7 +2214,7 @@ void MediaPlayerPrivateGStreamer::updateMaxTimeLoaded(double percentage)
     GST_DEBUG_OBJECT(pipeline(), "[Buffering] Updated maxTimeLoaded: %s", toString(m_maxTimeLoaded).utf8().data());
 }
 
-void MediaPlayerPrivateGStreamer::updateBufferingStatus(GstBufferingMode mode, double percentage, bool resetHistory)
+void MediaPlayerPrivateGStreamer::updateBufferingStatus(GstBufferingMode mode, double percentage, bool resetHistory, bool shouldUpdateStates)
 {
     m_wasBuffering = m_isBuffering;
     m_previousBufferingPercentage = m_bufferingPercentage;
@@ -2280,7 +2280,8 @@ void MediaPlayerPrivateGStreamer::updateBufferingStatus(GstBufferingMode mode, d
         m_previousBufferingPercentage = m_bufferingPercentage;
     }
     updateMaxTimeLoaded(percentage);
-    updateStates();
+    if (shouldUpdateStates)
+        updateStates();
     GST_TRACE("[Buffering] Settled results: m_wasBuffering: %s, m_isBuffering: %s, m_previousBufferingPercentage: %d, m_bufferingPercentage: %d",
         boolForPrinting(m_wasBuffering), boolForPrinting(m_isBuffering), m_previousBufferingPercentage, m_bufferingPercentage);
 }

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

@@ -542,7 +542,7 @@ class MediaPlayerPrivateGStreamer : public MediaPlayerPrivateInterface
 
     virtual void updateDownloadBufferingFlag();
     void processBufferingStats(GstMessage*);
-    void updateBufferingStatus(GstBufferingMode, double percentage, bool resetHistory = false);
+    void updateBufferingStatus(GstBufferingMode, double percentage, bool resetHistory = false, bool shouldUpdateStates = true);
     void updateMaxTimeLoaded(double percentage);
 
 #if USE(GSTREAMER_MPEGTS)