libkwineffects: Make parent optional in OffscreenQuickView

The parent argument is redundant if the view is managed with a smart
pointer.

src/libkwineffects/kwinoffscreenquickview.h

@@ -60,12 +60,12 @@ public:
      * Construct a new KWinQuickView
      * Export mode will be determined by the current effectsHandler
      */
-    OffscreenQuickView(QObject *parent);
+    explicit OffscreenQuickView(QObject *parent = nullptr);
 
     /**
      * Construct a new KWinQuickView explicitly stating an export mode
      */
-    OffscreenQuickView(ExportMode exportMode, QObject *parent);
+    explicit OffscreenQuickView(ExportMode exportMode, QObject *parent = nullptr);
 
     /**
      * Note that this may change the current GL Context
@@ -164,8 +164,8 @@ private:
 class KWINEFFECTS_EXPORT OffscreenQuickScene : public OffscreenQuickView
 {
 public:
-    OffscreenQuickScene(QObject *parent);
-    OffscreenQuickScene(ExportMode exportMode, QObject *parent);
+    explicit OffscreenQuickScene(QObject *parent = nullptr);
+    explicit OffscreenQuickScene(ExportMode exportMode, QObject *parent = nullptr);
     ~OffscreenQuickScene();
 
     /** top level item in the given source*/

src/plugins/kdecorations/aurorae/src/aurorae.cpp

@@ -288,7 +288,7 @@ bool Decoration::init()
         m_item->setParentItem(visualParent.value<QQuickItem *>());
         visualParent.value<QQuickItem *>()->setProperty("drawBackground", false);
     } else {
-        m_view = std::make_unique<KWin::OffscreenQuickView>(KWin::OffscreenQuickView::ExportMode::Image, this);
+        m_view = std::make_unique<KWin::OffscreenQuickView>(KWin::OffscreenQuickView::ExportMode::Image);
         m_item->setParentItem(m_view->contentItem());
         auto updateSize = [this]() {
             m_item->setSize(m_view->contentItem()->size());

src/plugins/showfps/showfpseffect.cpp

@@ -69,7 +69,7 @@ void ShowFpsEffect::prePaintScreen(ScreenPrePaintData &data, std::chrono::millis
     }
 
     if (!m_scene) {
-        m_scene = std::make_unique<OffscreenQuickScene>(nullptr);
+        m_scene = std::make_unique<OffscreenQuickScene>();
         const auto url = QUrl::fromLocalFile(QStandardPaths::locate(QStandardPaths::GenericDataLocation, QStringLiteral("kwin/effects/showfps/qml/main.qml")));
         m_scene->setSource(url, {{QStringLiteral("effect"), QVariant::fromValue(this)}});
     }