Changes to media probing API.

Added flush signals.

Change-Id: I9c124317e843c9b9011e69c44649ae9a4e974161
Reviewed-by: Dmytro Poplavskiy <dmytro.poplavskiy@nokia.com>

src/multimedia/controls/qmediavideoprobecontrol.cpp

@@ -92,6 +92,12 @@ QMediaVideoProbeControl::~QMediaVideoProbeControl()
     media service.
 */
 
+/*!
+    \fn QMediaVideoProbeControl::flush()
+
+    This signal should be emitted when it is required to release all frames.
+*/
+
 #include "moc_qmediavideoprobecontrol.cpp"
 
 QT_END_NAMESPACE