Move code around to fix build with system mesa.

gpu/GLES2/gl2chromium_constants.h

Index: gpu/GLES2/gl2chromium_constants.h
diff --git a/gpu/GLES2/gl2chromium_constants.h b/gpu/GLES2/gl2chromium_constants.h
new file mode 100644
index 0000000000000000000000000000000000000000..0e3b422926982e2636b811069f2db095bf21effe
--- /dev/null
+++ b/gpu/GLES2/gl2chromium_constants.h
@@ -0,0 +1,23 @@
+// Copyright (c) 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.
+
+// This file contains some GLES2 constants. There is a Chromium-specific need
+// to have them in a separate file.
+
+#ifndef GPU_GLES2_GL2CHROMIUM_CONSTANTS_H_
+#define GPU_GLES2_GL2CHROMIUM_CONSTANTS_H_
+
+#ifndef GL_DEPTH24_STENCIL8
+#define GL_DEPTH24_STENCIL8 0x88F0
+#endif
+
+/* GL_EXT_discard_framebuffer */
+#ifndef GL_EXT_discard_framebuffer
+#define GL_COLOR_EXT                                            0x1800
+#define GL_DEPTH_EXT                                            0x1801
+#define GL_STENCIL_EXT                                          0x1802
+#endif
+
+#endif  // GPU_GLES2_GL2CHROMIUM_CONSTANTS_H_
+