Implement QGstreamerVideoRenderer::stopRenderer()

Surface has to be stopped when
QGstreamerVideoRendererInterface::stopRenderer() is called.
This fixes a media player issue when video output is not cleared
when media is set to 0.

Change-Id: Ifdc851797519dcdf95db86e8dcec93b3866c388e
Reviewed-by: Dmytro Poplavskiy <dmytro.poplavskiy@nokia.com>

src/gsttools/qgstreamervideorenderer.cpp

@@ -69,6 +69,11 @@ GstElement *QGstreamerVideoRenderer::videoSink()
     return reinterpret_cast<GstElement*>(m_videoSink);
 }
 
+void QGstreamerVideoRenderer::stopRenderer()
+{
+    if (m_surface)
+        m_surface->stop();
+}
 
 QAbstractVideoSurface *QGstreamerVideoRenderer::surface() const
 {

src/multimedia/gsttools_headers/qgstreamervideorenderer_p.h

@@ -62,6 +62,7 @@ public:
 
     GstElement *videoSink();
 
+    void stopRenderer();
     bool isReady() const { return m_surface != 0; }
 
 signals: