ADS: Remove struct from DockAreaTitleBar

We do not use struct in Qt Creator.

Change-Id: Ieb5f9f4514a8220fa1d2a616baf2c8ef69d4a2c3
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

src/libs/advanceddockingsystem/dockareatitlebar.cpp

@@ -64,8 +64,9 @@ namespace ADS
     /**
      * Private data class of DockAreaTitleBar class (pimpl)
      */
-    struct DockAreaTitleBarPrivate
+    class DockAreaTitleBarPrivate
     {
+    public:
         DockAreaTitleBar *q;
         QPointer<TitleBarButtonType> m_tabsMenuButton;
         QPointer<TitleBarButtonType> m_undockButton;
@@ -124,8 +125,7 @@ namespace ADS
          * Makes the dock area floating
          */
         AbstractFloatingWidget *makeAreaFloating(const QPoint &offset, eDragState dragState);
-    }; // struct DockAreaTitleBarPrivate
-
+    }; // class DockAreaTitleBarPrivate
 
     DockAreaTitleBarPrivate::DockAreaTitleBarPrivate(DockAreaTitleBar *parent)
         : q(parent)

src/libs/advanceddockingsystem/dockareatitlebar.h

@@ -48,7 +48,7 @@ namespace ADS {
 
 class DockAreaTabBar;
 class DockAreaWidget;
-struct DockAreaTitleBarPrivate;
+class DockAreaTitleBarPrivate;
 
 using TitleBarButtonType = QToolButton;
 
@@ -106,7 +106,7 @@ class ADS_EXPORT DockAreaTitleBar : public QFrame
     Q_OBJECT
 private:
     DockAreaTitleBarPrivate *d; ///< private data (pimpl)
-    friend struct DockAreaTitleBarPrivate;
+    friend class DockAreaTitleBarPrivate;
 
     void onTabsMenuAboutToShow();
     void onCloseButtonClicked();

src/libs/advanceddockingsystem/dockwidget.h

@@ -80,7 +80,7 @@ protected:
     friend class DockAreaTabBar;
     friend class DockWidgetTab;
     friend class DockWidgetTabPrivate;
-    friend struct DockAreaTitleBarPrivate;
+    friend class DockAreaTitleBarPrivate;
 
     /**
      * Assigns the dock manager that manages this dock widget

src/libs/advanceddockingsystem/floatingdockcontainer.h

@@ -59,7 +59,7 @@ class DockAreaTabBar;
 class DockWidgetTab;
 class DockWidgetTabPrivate;
 class DockAreaTitleBar;
-struct DockAreaTitleBarPrivate;
+class DockAreaTitleBarPrivate;
 class FloatingWidgetTitleBar;
 class DockingStateReader;
 
@@ -118,7 +118,7 @@ private:
     friend class DockWidgetTabPrivate;
     friend class DockWidgetTab;
     friend class DockAreaTitleBar;
-    friend struct DockAreaTitleBarPrivate;
+    friend class DockAreaTitleBarPrivate;
     friend class DockWidget;
     friend class DockAreaWidget;
     friend class FloatingWidgetTitleBar;