gpu: Add support for GLX_EXT_texture_from_pixmap extension.

ui/gl/gl_image_mac.cc

+// 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 "ui/gl/gl_image.h"
+
+#include "base/debug/trace_event.h"
+#include "ui/gl/gl_image_stub.h"
+#include "ui/gl/gl_implementation.h"
+
+namespace gfx {
+
+scoped_refptr<GLImage> GLImage::CreatePixmapGLImage(
+    GLSurface* compatible_surface) {
+  TRACE_EVENT0("gpu", "GLImage::CreatePixmapGLImage");
+  switch (GetGLImplementation()) {
+    case kGLImplementationOSMesaGL:
+    case kGLImplementationDesktopGL:
+    case kGLImplementationAppleGL: {
+      return NULL;
+    }
+    case kGLImplementationMockGL:
+      return new GLImageStub;
+    default:
+      NOTREACHED();
+      return NULL;
+  }
+}
+
+}  // namespace gfx