Turn ScreenLockerWatcher into a KWIN_SINGLETON

It's created together with input, so that the input mechanismn already
has a way to check whether screen is locked.

Effects doesn't hold a member variable any more and instead uses the
singleton instance.

effects.cpp

@@ -102,7 +102,6 @@ EffectsHandlerImpl::EffectsHandlerImpl(Compositor *compositor, Scene *scene)
     , next_window_quad_type(EFFECT_QUAD_TYPE_START)
     , m_compositor(compositor)
     , m_scene(scene)
-    , m_screenLockerWatcher(new ScreenLockerWatcher(this))
     , m_desktopRendering(false)
     , m_currentRenderedDesktop(0)
     , m_effectLoader(new EffectLoader(this))
@@ -201,7 +200,7 @@ EffectsHandlerImpl::EffectsHandlerImpl(Compositor *compositor, Scene *scene)
     connect(tabBox, &TabBox::TabBox::tabBoxKeyEvent, this, &EffectsHandler::tabBoxKeyEvent);
 #endif
     connect(ScreenEdges::self(), &ScreenEdges::approaching, this, &EffectsHandler::screenEdgeApproaching);
-    connect(m_screenLockerWatcher, &ScreenLockerWatcher::locked, this, &EffectsHandler::screenLockingChanged);
+    connect(ScreenLockerWatcher::self(), &ScreenLockerWatcher::locked, this, &EffectsHandler::screenLockingChanged);
     // connect all clients
     for (Client *c : ws->clientList()) {
         setupClientConnections(c);
@@ -1482,7 +1481,7 @@ QString EffectsHandlerImpl::supportInformation(const QString &name) const
 
 bool EffectsHandlerImpl::isScreenLocked() const
 {
-    return m_screenLockerWatcher->isLocked();
+    return ScreenLockerWatcher::self()->isLocked();
 }
 
 QString EffectsHandlerImpl::debug(const QString& name, const QString& parameter) const

effects.h

@@ -59,7 +59,6 @@ class Compositor;
 class Deleted;
 class EffectLoader;
 class Unmanaged;
-class ScreenLockerWatcher;
 
 class KWIN_EXPORT EffectsHandlerImpl : public EffectsHandler
 {
@@ -289,7 +288,6 @@ private:
     QHash<QByteArray, qulonglong> m_managedProperties;
     Compositor *m_compositor;
     Scene *m_scene;
-    ScreenLockerWatcher *m_screenLockerWatcher;
     bool m_desktopRendering;
     int m_currentRenderedDesktop;
     Xcb::Window m_mouseInterceptionWindow;

main.cpp

@@ -30,6 +30,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "logind.h"
 #include "options.h"
 #include "screens.h"
+#include "screenlockerwatcher.h"
 #include "sm.h"
 #include "workspace.h"
 #include "xcbutils.h"
@@ -268,6 +269,7 @@ void Application::createWorkspace()
 
 void Application::createInput()
 {
+    ScreenLockerWatcher::create(this);
     LogindIntegration::create(this);
     auto input = InputRedirection::create(this);
     input->init();

screenlockerwatcher.cpp

@@ -27,6 +27,8 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 namespace KWin
 {
 
+KWIN_SINGLETON_FACTORY(ScreenLockerWatcher)
+
 static const QString SCREEN_LOCKER_SERVICE_NAME = QStringLiteral("org.freedesktop.ScreenSaver");
 
 ScreenLockerWatcher::ScreenLockerWatcher(QObject *parent)

screenlockerwatcher.h

@@ -22,6 +22,8 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 #include <QObject>
 
+#include <kwinglobals.h>
+
 class OrgFreedesktopScreenSaverInterface;
 class QDBusServiceWatcher;
 class QDBusPendingCallWatcher;
@@ -33,7 +35,6 @@ class ScreenLockerWatcher : public QObject
 {
     Q_OBJECT
 public:
-    explicit ScreenLockerWatcher(QObject *parent = 0);
     virtual ~ScreenLockerWatcher();
     bool isLocked() const {
         return m_locked;
@@ -50,6 +51,8 @@ private:
     OrgFreedesktopScreenSaverInterface *m_interface;
     QDBusServiceWatcher *m_serviceWatcher;
     bool m_locked;
+
+    KWIN_SINGLETON(ScreenLockerWatcher)
 };
 }