This change adds the apple software renderer as an option on Chrome/Mac. It's enabled by passing...

ui/gfx/gl/gl_switches.cc

 // Copyright (c) 2011 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/gfx/gl/gl_switches.h"
 
 namespace gfx {
 
 const char kGLImplementationDesktopName[]     = "desktop";
 const char kGLImplementationOSMesaName[]      = "osmesa";
+const char kGLImplementationAppleName[]       = "apple";
 const char kGLImplementationEGLName[]         = "egl";
 const char kGLImplementationSwiftShaderName[] = "swiftshader";
 const char kGLImplementationMockName[]        = "mock";
 
 }  // namespace gfx
 
 namespace switches {
 
 // Stop the GPU from synchronizing on the vsync before presenting.
 const char kDisableGpuVsync[]               = "disable-gpu-vsync";
@@ skipping 11 matching lines @@
 const char kUseGL[]                         = "use-gl";
 
 const char kSwiftShaderPath[]               = "swiftshader-path";
 
 // Inform Chrome that a GPU context will not be lost in power saving mode,
 // screen saving mode, etc.  Note that this flag does not ensure that a GPU
 // context will never be lost in any situations, say, a GPU reset.
 const char kGpuNoContextLost[]              = "gpu-no-context-lost";
 
 }  // namespace switches