Prettify calling of QMediaDevice signals

The idea is inheriting QPlatformMediaDevices from QObject and
connect it to QMediaDevice instances instead of manual collecting
and managing pointers.

Advantages:
- avoid UB behavior with static object destruction order in case
  a user makes any QMediaDevices static.
- align the signals parent: send singals from the QMediaDevice instance

Task-number: QTBUG-110071
Change-Id: I7c30694210864ff8c6c90c7299abdbf383f398fa
Reviewed-by: Pavel Dubsky <pavel.dubsky@qt.io>
Reviewed-by: Lars Knoll <lars@knoll.priv.no>
Reviewed-by: Jøger Hansegård <joger.hansegard@qt.io>
(cherry picked from commit a9471cbff3bf9d978620e6e962ea196acdd8dc0b)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/src/multimedia/platform/qplatformvideodevices.cpp b/src/multimedia/platform/qplatformvideodevices.cpp
index 9d2fc3c31..e556bb899 100644
--- a/src/multimedia/platform/qplatformvideodevices.cpp
+++ b/src/multimedia/platform/qplatformvideodevices.cpp
@@ -13,7 +13,7 @@ QPlatformVideoDevices::~QPlatformVideoDevices()
 
 void QPlatformVideoDevices::videoInputsChanged()
 {
-    QPlatformMediaDevices::instance()->videoInputsChanged();
+    emit QPlatformMediaDevices::instance()->videoInputsChanged();
 }
 
 QT_END_NAMESPACE