Mac: Remove dead IOSurface code

ui/gl/gl_image_io_surface.mm

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/gl/gl_image_io_surface.h"
 
 #include <map>
 
 #include "base/lazy_instance.h"
 #include "base/mac/foundation_util.h"
@@ skipping 10 matching lines @@
 // Note that this must be included after gl_bindings.h to avoid conflicts.
 #include <OpenGL/CGLIOSurface.h>
 #include <Quartz/Quartz.h>
 #include <stddef.h>
 
 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[] =
     "#extension GL_ARB_texture_rectangle : require";
 
 // clang-format off
 const char kVertexShader[] =
 STRINGIZE(
   attribute vec2 a_position;
   uniform vec2 a_texScale;
@@ skipping 359 matching lines @@
       GetGenericSharedMemoryGUIDForTracing(process_tracing_id, io_surface_id_);
   pmd->CreateSharedGlobalAllocatorDump(guid);
   pmd->AddOwnershipEdge(dump->guid(), guid);
 }
 
 base::ScopedCFTypeRef<IOSurfaceRef> GLImageIOSurface::io_surface() {
   return 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));
   return TextureFormat(format);
 }
 }  // namespace gl