winrt: Use ComPtr for better ref count tracking

Just forwarding the content of a ComPtr is potentially dangerous.

Change-Id: I4f3dfa04a5844d299a5653e31a4a0d1e1b86f9b5
Reviewed-by: Oliver Wolff <oliver.wolff@qt.io>

src/plugins/winrt/qwinrtcameracontrol.cpp

@@ -775,10 +775,10 @@ QCameraLocksControl *QWinRTCameraControl::cameraLocksControl() const
     return d->cameraLocksControl;
 }
 
-IMediaCapture *QWinRTCameraControl::handle() const
+Microsoft::WRL::ComPtr<ABI::Windows::Media::Capture::IMediaCapture> QWinRTCameraControl::handle() const
 {
     Q_D(const QWinRTCameraControl);
-    return d->capture.Get();
+    return d->capture;
 }
 
 void QWinRTCameraControl::onBufferRequested()

src/plugins/winrt/qwinrtcameracontrol.h

@@ -40,6 +40,8 @@
 #include <QtMultimedia/QCameraControl>
 #include <QtCore/qt_windows.h>
 
+#include <wrl.h>
+
 namespace ABI {
     namespace Windows {
         namespace Media {
@@ -90,7 +92,7 @@ public:
     QCameraFocusControl *cameraFocusControl() const;
     QCameraLocksControl *cameraLocksControl() const;
 
-    ABI::Windows::Media::Capture::IMediaCapture *handle() const;
+    Microsoft::WRL::ComPtr<ABI::Windows::Media::Capture::IMediaCapture> handle() const;
 
     bool setFocus(QCameraFocus::FocusModes mode);
     bool setFocusPoint(const QPointF &point);

src/plugins/winrt/qwinrtcameraimagecapturecontrol.cpp

@@ -147,7 +147,7 @@ int QWinRTCameraImageCaptureControl::capture(const QString &fileName)
     Q_D(QWinRTCameraImageCaptureControl);
 
     ++d->currentCaptureId;
-    IMediaCapture *capture = d->cameraControl->handle();
+    ComPtr<IMediaCapture> capture = d->cameraControl->handle();
     if (!capture) {
         emit error(d->currentCaptureId, QCameraImageCapture::NotReadyError, tr("Camera not ready"));
         return -1;