feat(overlay): inherit zoom and add zoom factor (#6016)

src/widgets/OverlayWindow.hpp

@@ -1,6 +1,7 @@
 #pragma once
 
 #include "common/Channel.hpp"
+#include "widgets/BaseWindow.hpp"
 #include "widgets/helper/ChannelView.hpp"
 #include "widgets/helper/OverlayInteraction.hpp"
 
@@ -17,7 +18,7 @@ class QGraphicsDropShadowEffect;
 
 namespace chatterino {
 
-class OverlayWindow : public QWidget
+class OverlayWindow : public BaseWindow
 {
     Q_OBJECT
 public:
@@ -52,11 +53,13 @@ protected:
                      NativeResult *result) override;
 #endif
 
+    void addShortcuts() override;
+
+    float desiredScale() const override;
+
 private:
     void triggerFirstActivation();
 
-    void addShortcuts();
-
     void startInteraction();
     void startShortInteraction();
     void endInteraction();
@@ -70,7 +73,6 @@ private:
 #endif
 
     IndirectChannel channel_;
-    pajlada::Signals::SignalHolder holder_;
 
     ChannelView channelView_;
     QGraphicsDropShadowEffect *dropShadow_;