Centralize rowCount calculation

Change-Id: I6e159702e533848c9eb9c98551743d5472f2155c
Reviewed-by: Kai Koehne <kai.koehne@digia.com>

plugins/qmlprofilerextension/scenegraphtimelinemodel.cpp

@@ -101,8 +101,6 @@ class SceneGraphTimelineModel::SceneGraphTimelineModelPrivate :
         public AbstractTimelineModel::AbstractTimelineModelPrivate
 {
 public:
-    SceneGraphTimelineModelPrivate();
-    int collapsedRowCount;
     void flattenLoads();
 
     QVector<SceneGraphEvent> data;
@@ -110,11 +108,6 @@ private:
     Q_DECLARE_PUBLIC(SceneGraphTimelineModel)
 };
 
-SceneGraphTimelineModel::SceneGraphTimelineModelPrivate::SceneGraphTimelineModelPrivate() :
-    collapsedRowCount(1)
-{
-}
-
 SceneGraphTimelineModel::SceneGraphTimelineModel(QObject *parent)
     : AbstractTimelineModel(new SceneGraphTimelineModelPrivate,
                             tr(QmlProfilerModelManager::featureName(QmlDebug::ProfileSceneGraph)),
@@ -127,14 +120,6 @@ quint64 SceneGraphTimelineModel::features() const
     return 1 << QmlDebug::ProfileSceneGraph;
 }
 
-int SceneGraphTimelineModel::rowCount() const
-{
-    Q_D(const SceneGraphTimelineModel);
-    if (isEmpty())
-        return 1;
-    return expanded() ? (MaximumSceneGraphStage + 1) : d->collapsedRowCount;
-}
-
 int SceneGraphTimelineModel::row(int index) const
 {
     Q_D(const SceneGraphTimelineModel);
@@ -329,6 +314,7 @@ void SceneGraphTimelineModel::SceneGraphTimelineModelPrivate::flattenLoads()
 
     // Starting from 0, count is maxIndex+1
     collapsedRowCount++;
+    expandedRowCount = MaximumSceneGraphStage + 1;
 }
 
 void SceneGraphTimelineModel::clear()