Qt: Use signals for emu_thread start/stop and fix disasm widget.

src/citra_qt/main.h

@@ -5,6 +5,7 @@
 #ifndef _CITRA_QT_MAIN_HXX_
 #define _CITRA_QT_MAIN_HXX_
 
+#include <memory>
 #include <QMainWindow>
 
 #include "ui_main.h"
@@ -35,9 +36,23 @@ public:
     GMainWindow();
     ~GMainWindow();
 
-    EmuThread* GetEmuThread() {
-        return emu_thread;
-    }
+signals:
+
+    /**
+     * Signal that is emitted when a new EmuThread has been created and an emulation session is
+     * about to start. At this time, the core system emulation has been initialized, and all
+     * emulation handles and memory should be valid.
+     *
+     * @param emu_thread Pointer to the newly created EmuThread (to be used by widgets that need to
+     *      access/change emulation state).
+     */
+    void EmulationStarting(EmuThread* emu_thread);
+
+    /**
+     * Signal that is emitted when emulation is about to stop. At this time, the EmuThread and core
+     * system emulation handles and memory are still valid, but are about become invalid.
+     */
+    void EmulationStopping();
 
 private:
     void BootGame(std::string filename);
@@ -60,7 +75,8 @@ private:
     Ui::MainWindow ui;
 
     GRenderWindow* render_window;
-    EmuThread* emu_thread;
+
+    std::unique_ptr<EmuThread> emu_thread;
 
     ProfilerWidget* profilerWidget;
     DisassemblerWidget* disasmWidget;