Massive refactoring of xenia::ui and GL swap behavior.

This seems to dramatically improve most games (especially with
--vsync=false), though it may cause swap issues with others.
New code should be easier to port, and enables elemental-forms to be
drawn for any emulator UI.

src/xenia/ui/loop_win.h

@@ -0,0 +1,60 @@
+/**
+ ******************************************************************************
+ * Xenia : Xbox 360 Emulator Research Project                                 *
+ ******************************************************************************
+ * Copyright 2014 Ben Vanik. All rights reserved.                             *
+ * Released under the BSD license - see LICENSE in the root for more details. *
+ ******************************************************************************
+ */
+
+#ifndef XENIA_UI_LOOP_WIN_H_
+#define XENIA_UI_LOOP_WIN_H_
+
+#include <mutex>
+#include <list>
+#include <thread>
+
+#include "xenia/base/mutex.h"
+#include "xenia/base/platform.h"
+#include "xenia/base/threading.h"
+#include "xenia/ui/loop.h"
+
+namespace xe {
+namespace ui {
+
+class Win32Loop : public Loop {
+ public:
+  Win32Loop();
+  ~Win32Loop() override;
+
+  void Post(std::function<void()> fn) override;
+  void PostDelayed(std::function<void()> fn, uint64_t delay_millis) override;
+
+  void Quit() override;
+  void AwaitQuit() override;
+
+ private:
+  struct PendingTimer {
+    Win32Loop* loop;
+    HANDLE timer_queue;
+    HANDLE timer_handle;
+    std::function<void()> fn;
+  };
+
+  void ThreadMain();
+
+  static void TimerQueueCallback(void* context, uint8_t);
+
+  std::thread thread_;
+  DWORD thread_id_;
+  xe::threading::Fence quit_fence_;
+
+  HANDLE timer_queue_;
+  xe::mutex pending_timers_mutex_;
+  std::list<PendingTimer*> pending_timers_;
+};
+
+}  // namespace ui
+}  // namespace xe
+
+#endif  // XENIA_UI_LOOP_WIN_H_