Expose availability from the backend to C++ and QML.

The availabilityError property was static based on the service, but it
can change at run time, so add the plumbing to allow the backend to
report it itself.

Also make sure that both QML and C++ expose the availability.

The radio tuner and data controls previously had properties (but no
signals) for availability - these have been removed.

Change-Id: I9240cf93e2a51b14cd38642f9312ae3c75f05361
Reviewed-by: Ling Hu <ling.hu@nokia.com>

src/multimedia/controls/qmediaavailabilitycontrol.h

@@ -0,0 +1,78 @@
+/****************************************************************************
+**
+** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/
+**
+** This file is part of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** GNU Lesser General Public License Usage
+** This file may be used under the terms of the GNU Lesser General Public
+** License version 2.1 as published by the Free Software Foundation and
+** appearing in the file LICENSE.LGPL included in the packaging of this
+** file. Please review the following information to ensure the GNU Lesser
+** General Public License version 2.1 requirements will be met:
+** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights. These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU General
+** Public License version 3.0 as published by the Free Software Foundation
+** and appearing in the file LICENSE.GPL included in the packaging of this
+** file. Please review the following information to ensure the GNU General
+** Public License version 3.0 requirements will be met:
+** http://www.gnu.org/copyleft/gpl.html.
+**
+** Other Usage
+** Alternatively, this file may be used in accordance with the terms and
+** conditions contained in a signed written agreement between you and Nokia.
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QMEDIAAVAILABILITYCONTROL_H
+#define QMEDIAAVAILABILITYCONTROL_H
+
+#include <qmediacontrol.h>
+#include <qmediaobject.h>
+#include <qtmedianamespace.h>
+
+QT_BEGIN_HEADER
+
+QT_BEGIN_NAMESPACE
+
+QT_MODULE(Multimedia)
+
+class Q_MULTIMEDIA_EXPORT QMediaAvailabilityControl : public QMediaControl
+{
+    Q_OBJECT
+
+public:
+    ~QMediaAvailabilityControl();
+
+    virtual QtMultimedia::AvailabilityError availability() const = 0;
+
+signals:
+    void availabilityChanged(QtMultimedia::AvailabilityError availability);
+
+protected:
+    QMediaAvailabilityControl(QObject* parent = 0);
+};
+
+#define QMediaAvailabilityControl_iid "com.nokia.Qt.QMediaAvailabilityControl/1.0"
+Q_MEDIA_DECLARE_CONTROL(QMediaAvailabilityControl, QMediaAvailabilityControl_iid)
+
+QT_END_NAMESPACE
+
+QT_END_HEADER
+
+#endif // QMEDIAAVAILABILITYCONTROL_H