Add cairo interface.

src/windows/ui_interfaces/x11/XcbWindow.cpp

@@ -0,0 +1,22 @@
+#include "XcbWindow.h"
+
+XcbWindow::XcbWindow(int hwnd)
+    : mHandle(hwnd)
+{
+
+}
+
+std::unique_ptr<XcbWindow> XcbWindow::Create(int hwnd)
+{
+    return std::make_unique<XcbWindow>(hwnd);
+}
+
+int XcbWindow::GetHandle() const
+{
+    return mHandle;
+}
+
+unsigned XcbWindow::GetGraphicsContext() const
+{
+    return mGraphicsContext;
+}