FDO Secrets: Fix double free on exit

* Prevent double free due to QObject cleanup happening before/after the ExtraPage  storing the QSharedPointer to FdoSecretsPlugin is deleted.
* Fixes #4877

src/fdosecrets/FdoSecretsPlugin.cpp

@@ -30,13 +30,21 @@
 
 using FdoSecrets::Service;
 
+// TODO: Only used for testing. Need to split service functions away from settings page.
+QPointer<FdoSecretsPlugin> g_fdoSecretsPlugin;
+
 FdoSecretsPlugin::FdoSecretsPlugin(DatabaseTabWidget* tabWidget)
-    : QObject(tabWidget)
+    : m_dbTabs(tabWidget)
-    , m_dbTabs(tabWidget)
 {
+    g_fdoSecretsPlugin = this;
     FdoSecrets::registerDBusTypes();
 }
 
+FdoSecretsPlugin* FdoSecretsPlugin::getPlugin()
+{
+    return g_fdoSecretsPlugin;
+}
+
 QWidget* FdoSecretsPlugin::createWidget()
 {
     return new SettingsWidgetFdoSecrets(this);

src/fdosecrets/FdoSecretsPlugin.h

@@ -70,6 +70,9 @@ public:
      */
     QString reportExistingService() const;
 
+    // TODO: Only used for testing. Need to split service functions away from settings page.
+    static FdoSecretsPlugin* getPlugin();
+
 public slots:
     void emitRequestSwitchToDatabases();
     void emitRequestShowNotification(const QString& msg, const QString& title = {});

tests/gui/TestGuiFdoSecrets.cpp

@@ -200,7 +200,7 @@ void TestGuiFdoSecrets::initTestCase()
     m_mainWindow.reset(new MainWindow());
     m_tabWidget = m_mainWindow->findChild<DatabaseTabWidget*>("tabWidget");
     QVERIFY(m_tabWidget);
-    m_plugin = m_mainWindow->findChild<FdoSecretsPlugin*>();
+    m_plugin = FdoSecretsPlugin::getPlugin();
     QVERIFY(m_plugin);
     m_mainWindow->show();