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    <body><span class="vcard"><a class="email" href="mailto:mcatanzaro&#64;igalia.com" title="Michael Catanzaro &lt;mcatanzaro&#64;igalia.com&gt;"> <span class="fn">Michael Catanzaro</span></a>
</span> changed
              <a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - [GStreamer][Stable] Crashes during plugin installation"
   href="https://bugs.webkit.org/show_bug.cgi?id=144099">bug 144099</a>
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          <tr>
            <th>What</th>
            <th>Removed</th>
            <th>Added</th>
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           <td style="text-align:right;">Summary</td>
           <td>[GStreamer] Crashes during plugin installation
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           <td>[GStreamer][Stable] Crashes during plugin installation
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            <b><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - [GStreamer][Stable] Crashes during plugin installation"
   href="https://bugs.webkit.org/show_bug.cgi?id=144099#c6">Comment # 6</a>
              on <a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - [GStreamer][Stable] Crashes during plugin installation"
   href="https://bugs.webkit.org/show_bug.cgi?id=144099">bug 144099</a>
              from <span class="vcard"><a class="email" href="mailto:mcatanzaro&#64;igalia.com" title="Michael Catanzaro &lt;mcatanzaro&#64;igalia.com&gt;"> <span class="fn">Michael Catanzaro</span></a>
</span></b>
        <pre>Here is the order of some relevant function calls:

virtual GstElement *WebCore::MediaPlayerPrivateGStreamer::createAudioSink(): player=0x7f2a2f088000

(WebKitWebProcess:14021): GLib-GObject-WARNING **: invalid (NULL) pointer instance

(WebKitWebProcess:14021): GLib-GObject-CRITICAL **: g_signal_connect_data: assertion 'G_TYPE_CHECK_INSTANCE (instance)' failed

(WebKitWebProcess:14021): GStreamer-CRITICAL **: gst_element_link_pads_full: assertion 'GST_IS_ELEMENT (dest)' failed
gboolean WebCore::MediaPlayerPrivateGStreamer::handleMessage(GstMessage *): Beginning plugin installation, player=0x7f2a2f088000
virtual WebCore::MediaPlayerPrivateGStreamer::~MediaPlayerPrivateGStreamer(): player=0x7f2a2f088000

So you are right on both counts, the invalid (NULL) pointer instance warning is unrelated to the plugin installation crash, and the media player object is deleted prior to the plugin installation callback (though that does not cause any crash in trunk). I have filed <a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - Critical warnings when loading YouTube videos"
   href="show_bug.cgi?id=146999">bug #146999</a> for the invalid (NULL) pointer instance issue. Since the plugin installation crash doesn't occur in trunk, I will mark this bug as [Stable].

By the way, in 2.8 I expect you would be able to reproduce by uninstalling gstreamer1.0-libav.</pre>
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