RequestSwap to force a swap from the GL thread.

src/xenia/gpu/gl4/command_processor.h

@@ -43,6 +43,11 @@ struct SwapParameters {
   GLenum attachment;
 };
 
+enum class SwapMode {
+  kNormal,
+  kIgnored,
+};
+
 class CommandProcessor {
  public:
   CommandProcessor(GL4GraphicsSystem* graphics_system);
@@ -59,6 +64,9 @@ class CommandProcessor {
   void Shutdown();
   void CallInThread(std::function<void()> fn);
 
+  void set_swap_mode(SwapMode swap_mode) { swap_mode_ = swap_mode; }
+  void IssueSwap();
+
   void BeginTracing(const std::wstring& root_path);
   void EndTracing();
 
@@ -207,6 +215,8 @@ class CommandProcessor {
   std::function<void()> pending_fn_;
   HANDLE pending_fn_event_;
 
+  SwapMode swap_mode_;
+
   uint64_t time_base_;
   uint32_t counter_;