Help: Provide a button for re-indexing the documentation

It sometimes just breaks, so having a simple way for re-indexing seems
appropriate.

Task-number: QTCREATORBUG-11484
Change-Id: I4010d31cbe04f9ef57ebe772610118d8aa7a2ea2
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@digia.com>
Reviewed-by: Alessandro Portale <alessandro.portale@digia.com>

src/plugins/help/searchwidget.h

@@ -30,9 +30,10 @@
 #ifndef SEARCHWIDGET_H
 #define SEARCHWIDGET_H
 
+#include <coreplugin/sidebar.h>
+
 #include <QFutureInterface>
 #include <QFutureWatcher>
-
 #include <QWidget>
 
 QT_BEGIN_NAMESPACE
@@ -45,6 +46,19 @@ QT_END_NAMESPACE
 namespace Help {
 namespace Internal {
 
+class SearchSideBarItem : public Core::SideBarItem
+{
+    Q_OBJECT
+
+public:
+    SearchSideBarItem();
+
+    QList<QToolButton *> createToolBarWidgets();
+
+signals:
+    void linkActivated(const QUrl &url);
+};
+
 class SearchWidget : public QWidget
 {
     Q_OBJECT