wayland: Make workspace responsible for creating Screens

The Screens object is created by Workspace on X11. This change makes X11
and Wayland behave more similar. As is, the Screens is a helper for
window management code, don't use it in backends. Note that the X11 backend
already uses the Screens, it needs to be addressed individually.

autotests/integration/kwin_wayland_test.cpp

@@ -153,7 +153,6 @@ void WaylandTestApplication::performStartup()
 void WaylandTestApplication::continueStartupWithScreens()
 {
     disconnect(kwinApp()->platform(), &Platform::screensQueried, this, &WaylandTestApplication::continueStartupWithScreens);
-    createScreens();
     WaylandCompositor::create();
     connect(Compositor::self(), &Compositor::sceneCreated, this, &WaylandTestApplication::continueStartupWithScene);
 }

src/main.cpp

@@ -12,15 +12,14 @@
 #include <config-kwin.h>
 
 #include "atoms.h"
-#include "platform.h"
 #include "colormanager.h"
 #include "composite.h"
 #include "cursor.h"
 #include "input.h"
 #include "inputmethod.h"
 #include "options.h"
+#include "platform.h"
 #include "pluginmanager.h"
-#include "screens.h"
 #if KWIN_BUILD_SCREENLOCKER
 #include "screenlockerwatcher.h"
 #endif
@@ -280,15 +279,6 @@ void Application::createInput()
     m_platform->createPlatformCursor(this);
 }
 
-void Application::createScreens()
-{
-    if (Screens::self()) {
-        return;
-    }
-    Screens::create(this);
-    Q_EMIT screensCreated();
-}
-
 void Application::createAtoms()
 {
     atoms = new Atoms;

src/main.h

@@ -138,7 +138,6 @@ public:
         }
     }
     void updateX11Time(xcb_generic_event_t *event);
-    void createScreens();
 
     static void setCrashCount(int count);
     static bool wasCrash();
@@ -238,7 +237,6 @@ Q_SIGNALS:
     void x11ConnectionAboutToBeDestroyed();
     void xwaylandScaleChanged();
     void workspaceCreated();
-    void screensCreated();
     void platformCreated();
     void virtualTerminalCreated();
     void started();

src/main_wayland.cpp

@@ -149,7 +149,6 @@ void ApplicationWayland::performStartup()
     TabletModeManager::create(this);
     createPlugins();
 
-    createScreens();
     WaylandCompositor::create();
 
     connect(Compositor::self(), &Compositor::sceneCreated, platform(), &Platform::sceneInitialized);

src/workspace.cpp

@@ -157,7 +157,7 @@ Workspace::Workspace()
 
     RuleBook::create(this)->load();
 
-    kwinApp()->createScreens();
+    Screens::create(this);
     ScreenEdges::create(this);
 
     // VirtualDesktopManager needs to be created prior to init shortcuts