Emu: always use Emu.Quit() to quit RPCS3

This creates a single possible point of failure for calling quit()

rpcs3/Emu/System.cpp

@@ -1752,19 +1752,6 @@ void Emulator::Stop(bool restart)
 
 	vm::close();
 
-	if (do_exit)
-	{
-		GetCallbacks().exit(true);
-	}
-	else
-	{
-		if (full_stop)
-		{
-			GetCallbacks().exit(false);
-		}
-		Init();
-	}
-
 #ifdef LLVM_AVAILABLE
 	extern void jit_finalize();
 	jit_finalize();
@@ -1793,6 +1780,24 @@ void Emulator::Stop(bool restart)
 	{
 		enable_display_sleep();
 	}
+
+	if (do_exit || full_stop)
+	{
+		if (Quit(do_exit))
+		{
+			return;
+		}
+	}
+
+	Init();
+}
+
+bool Emulator::Quit(bool force_quit) const
+{
+	Emu.SetForceBoot(false);
+	Emu.Stop();
+
+	return GetCallbacks().exit(force_quit);
 }
 
 std::string Emulator::GetFormattedTitle(double fps) const

rpcs3/Emu/System.h

@@ -37,7 +37,7 @@ struct EmuCallbacks
 	std::function<void()> on_resume;
 	std::function<void()> on_stop;
 	std::function<void()> on_ready;
-	std::function<void(bool)> exit; // (force_quit) close RPCS3
+	std::function<bool(bool)> exit; // (force_quit) close RPCS3
 	std::function<void(s32, s32)> handle_taskbar_progress; // (type, value) type: 0 for reset, 1 for increment, 2 for set_limit
 	std::function<void()> init_kb_handler;
 	std::function<void()> init_mouse_handler;
@@ -202,6 +202,7 @@ public:
 	void Resume();
 	void Stop(bool restart = false);
 	void Restart() { Stop(true); }
+	bool Quit(bool force_quit) const;
 
 	bool IsRunning() const { return m_state == system_state::running; }
 	bool IsPaused()  const { return m_state == system_state::paused; }

rpcs3/headless_application.cpp

@@ -39,12 +39,15 @@ void headless_application::InitializeCallbacks()
 {
 	EmuCallbacks callbacks = CreateCallbacks();
 
-	callbacks.exit = [this](bool force_quit)
+	callbacks.exit = [this](bool force_quit) -> bool
 	{
 		if (force_quit)
 		{
 			quit();
+			return true;
 		}
+
+		return false;
 	};
 	callbacks.call_after = [=, this](std::function<void()> func)
 	{

rpcs3/rpcs3qt/gui_application.cpp

@@ -267,13 +267,21 @@ void gui_application::InitializeCallbacks()
 {
 	EmuCallbacks callbacks = CreateCallbacks();
 
-	callbacks.exit = [this](bool force_quit)
+	callbacks.exit = [this](bool force_quit) -> bool
 	{
 		// Close rpcs3 if closed in no-gui mode
 		if (force_quit || !m_main_window)
 		{
-			quit();
+			if (m_main_window)
+			{
+				// Close main window in order to save its window state
+				m_main_window->close();
 			}
+			quit();
+			return true;
+		}
+
+		return false;
 	};
 	callbacks.call_after = [this](std::function<void()> func)
 	{

rpcs3/rpcs3qt/main_window.cpp

@@ -72,6 +72,7 @@ main_window::main_window(std::shared_ptr<gui_settings> gui_settings, std::shared
 
 main_window::~main_window()
 {
+	SaveWindowState();
 	delete ui;
 }
 
@@ -2140,7 +2141,7 @@ void main_window::mouseDoubleClickEvent(QMouseEvent *event)
 	}
 }
 
-/** Override the Qt close event to have the emulator stop and the application die.  May add a warning dialog in future.
+/** Override the Qt close event to have the emulator stop and the application die.
 */
 void main_window::closeEvent(QCloseEvent* closeEvent)
 {
@@ -2150,13 +2151,8 @@ void main_window::closeEvent(QCloseEvent* closeEvent)
 		return;
 	}
 
-	// Cleanly stop the emulator.
-	Emu.Stop();
-
-	SaveWindowState();
-
-	// It's possible to have other windows open, like games.  So, force the application to die.
-	QApplication::quit();
+	// Cleanly stop and quit the emulator.
+	Emu.Quit(true);
 }
 
 /**