Gstreamer media backend cleanup.

Moved controls specific bus/sync messages handling from
player/camera/capture session to corresponding controls.

Reviewed-by: Michael Goddard
Change-Id: Ieb67976ed335b0ef1cde87dc60e8ad8da3409526
Reviewed-on: http://codereview.qt.nokia.com/2535
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Michael Goddard <michael.goddard@nokia.com>

src/plugins/gstreamer/camerabin/camerabinsession.h

@@ -76,10 +76,13 @@ public:
     virtual GstElement *buildElement() = 0;
 };
 
-class CameraBinSession : public QObject, public QGstreamerSyncEventFilter
+class CameraBinSession : public QObject,
+                         public QGstreamerBusMessageFilter,
+                         public QGstreamerSyncMessageFilter
 {
     Q_OBJECT
     Q_PROPERTY(qint64 duration READ duration NOTIFY durationChanged)
+    Q_INTERFACES(QGstreamerBusMessageFilter QGstreamerSyncMessageFilter)
 public:
     enum CameraRole {
        FrontCamera, // Secondary camera
@@ -91,6 +94,7 @@ public:
 
     GstPhotography *photography();
     GstElement *cameraBin() { return m_pipeline; }
+    QGstreamerBusHelper *bus() { return m_busHelper; }
 
     CameraRole cameraRole() const;
 
@@ -146,6 +150,7 @@ public:
     bool isMuted() const;
 
     bool processSyncMessage(const QGstreamerMessage &message);
+    bool processBusMessage(const QGstreamerMessage &message);
 
 signals:
     void stateChanged(QCamera::State state);
@@ -157,7 +162,6 @@ signals:
     void viewfinderChanged();
     void readyChanged(bool);
     void busyChanged(bool);
-    void busMessage(const QGstreamerMessage &message);
 
 public slots:
     void setDevice(const QString &device);
@@ -167,7 +171,6 @@ public slots:
     void setMuted(bool);
 
 private slots:
-    void handleBusMessage(const QGstreamerMessage &message);
     void handleViewfinderChange();
 
 private: