GPU: Further improve vsync handling

src/util/platform_misc.h

@@ -23,4 +23,10 @@ bool PlaySoundAsync(const char* path);
 namespace Host {
 /// Return the current window handle. Needed for DInput.
 std::optional<WindowInfo> GetTopLevelWindowInfo();
-} // namespace Host
+} // namespace Host
+
+// TODO: Move all the other Cocoa stuff in here.
+namespace CocoaTools {
+/// Returns the refresh rate of the display the window is placed on.
+std::optional<float> GetViewRefreshRate(const WindowInfo& wi);
+}