Mac: Remove dead IOSurface code

ui/gl/gl_image_io_surface.mm

Index: ui/gl/gl_image_io_surface.mm
diff --git a/ui/gl/gl_image_io_surface.mm b/ui/gl/gl_image_io_surface.mm
index 3059333cc8896feb96c15f2b4147e3e927a3f417..e0d08003c8928a4db3b23db0646005d040afaba3 100644
--- a/ui/gl/gl_image_io_surface.mm
+++ b/ui/gl/gl_image_io_surface.mm
@@ -28,9 +28,6 @@ using gfx::BufferFormat;
 namespace gl {
 namespace {
 
-using WidgetToLayerMap = std::map<gfx::AcceleratedWidget, CALayer*>;
-base::LazyInstance<WidgetToLayerMap> g_widget_to_layer_map;
-
 const char kGLSLVersion[] = "#version 110";
 
 const char kTextureRectangleRequired[] =
@@ -410,15 +407,6 @@ base::ScopedCFTypeRef<IOSurfaceRef> GLImageIOSurface::io_surface() {
 }
 
 // static
-void GLImageIOSurface::SetLayerForWidget(gfx::AcceleratedWidget widget,
-                                         CALayer* layer) {
-  if (layer)
-    g_widget_to_layer_map.Pointer()->insert(std::make_pair(widget, layer));
-  else
-    g_widget_to_layer_map.Pointer()->erase(widget);
-}
-
-// static
 unsigned GLImageIOSurface::GetInternalFormatForTesting(
     gfx::BufferFormat format) {
   DCHECK(ValidFormat(format));