Add a basic NativeViewportMac for Mojo

ui/gl/gl_context_mac.mm

 // Copyright (c) 2012 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 "base/basictypes.h"
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "third_party/mesa/src/include/GL/osmesa.h"
 #include "ui/gl/gl_context_cgl.h"
+#include "ui/gl/gl_context_nsview.h"
 #include "ui/gl/gl_context_osmesa.h"
 #include "ui/gl/gl_context_stub.h"
 #include "ui/gl/gl_implementation.h"
 #include "ui/gl/gl_surface.h"
 #include "ui/gl/gl_switches.h"
 
-#if defined(USE_AURA)
-#include "ui/gl/gl_context_nsview.h"
-#endif
-
 namespace gfx {
 
 class GLShareGroup;
 
 scoped_refptr<GLContext> GLContext::CreateGLContext(
     GLShareGroup* share_group,
     GLSurface* compatible_surface,
     GpuPreference gpu_preference) {
   TRACE_EVENT0("gpu", "GLContext::CreateGLContext");
   switch (GetGLImplementation()) {
     case kGLImplementationDesktopGL:
     case kGLImplementationAppleGL: {
       scoped_refptr<GLContext> context;
-#if defined(USE_AURA)
       if (compatible_surface->IsOffscreen())
         context = new GLContextCGL(share_group);
       else
         context = new GLContextNSView(share_group);
-#else
-      context = new GLContextCGL(share_group);
-#endif // USE_AURA
       if (!context->Initialize(compatible_surface, gpu_preference))
         return NULL;
 
       return context;
     }
     case kGLImplementationOSMesaGL: {
       scoped_refptr<GLContext> context(new GLContextOSMesa(share_group));
       if (!context->Initialize(compatible_surface, gpu_preference))
         return NULL;
 
       return context;
     }
     case kGLImplementationMockGL:
       return new GLContextStub;
     default:
       NOTREACHED();
       return NULL;
   }
 }
 
 }  // namespace gfx