Prevent static mojo builds from pulling //ui/gl into mojo_shell

gpu/command_buffer/client/gpu_switches.h

+// Copyright (c) 2014 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.
+
+// Defines all the command-line switches used by gpu/command_buffer/client/.
+
+#ifndef GPU_COMMAND_BUFFER_CLIENT_GPU_SWITCHES_H_
+#define GPU_COMMAND_BUFFER_CLIENT_GPU_SWITCHES_H_
+
+#include "gpu/command_buffer/client/gles2_impl_export.h"
+
+namespace switches {
+
+GLES2_IMPL_EXPORT extern const char kEnableGPUClientLogging[];
+
+}  // namespace switches
+
+#endif  // GPU_COMMAND_BUFFER_CLIENT_GPU_SWITCHES_H_
+