Delay kit initialization until after the UI is up

This can potentially be expensive, so delay it.

Side effect is that the "History:" label in the Search Result
OutputPane is now correctly rendered:-) That was broken since
the Kit initialization triggered an event loop to be run too
early by running a SynchronousProcess.

Change-Id: I905c33c6facbbe03f22b9860c277ec658af9326e
Reviewed-by: Tobias Hunger <tobias.hunger@theqtcompany.com>

src/plugins/projectexplorer/projectexplorer.cpp

@@ -1257,10 +1257,6 @@ bool ProjectExplorerPlugin::initialize(const QStringList &arguments, QString *er
     connect(buildManager, &BuildManager::buildQueueFinished,
             dd, &ProjectExplorerPluginPrivate::buildQueueFinished, Qt::QueuedConnection);
 
-    connect(ICore::instance(), &ICore::coreAboutToOpen,
-            dd, &ProjectExplorerPluginPrivate::determineSessionToRestoreAtStartup);
-    connect(ICore::instance(), &ICore::coreOpened,
-            dd, &ProjectExplorerPluginPrivate::restoreSession);
     connect(ICore::instance(), &ICore::newItemDialogRunningChanged, updateActions);
     connect(ICore::instance(), &ICore::newItemDialogRunningChanged,
             dd, &ProjectExplorerPluginPrivate::updateContextMenuActions);
@@ -1506,9 +1502,16 @@ void ProjectExplorerPlugin::extensionsInitialized()
     BuildManager::extensionsInitialized();
 
     DeviceManager::instance()->addDevice(IDevice::Ptr(new DesktopDevice));
+}
+
+bool ProjectExplorerPlugin::delayedInitialize()
+{
+    dd->determineSessionToRestoreAtStartup();
     DeviceManager::instance()->load();
     ToolChainManager::restoreToolChains();
     dd->m_kitManager->restoreKits();
+    QTimer::singleShot(0, dd, &ProjectExplorerPluginPrivate::restoreSession); // delay a bit...
+    return true;
 }
 
 void ProjectExplorerPluginPrivate::updateRunWithoutDeployMenu()

src/plugins/projectexplorer/projectexplorer.h

@@ -120,6 +120,7 @@ public:
     //PluginInterface
     bool initialize(const QStringList &arguments, QString *errorMessage) override;
     void extensionsInitialized() override;
+    bool delayedInitialize() override;
     ShutdownFlag aboutToShutdown() override;
 
     static void setProjectExplorerSettings(const Internal::ProjectExplorerSettings &pes);