Support ozone=1 compositor_unittests with OSMesa

ui/gl/gl_implementation_linux.h

Index: ui/gl/gl_implementation_linux.h
diff --git a/ui/gl/gl_implementation_linux.h b/ui/gl/gl_implementation_linux.h
new file mode 100644
index 0000000000000000000000000000000000000000..6f7151934738d2b8606dc63b3ed322124b5b3549
--- /dev/null
+++ b/ui/gl/gl_implementation_linux.h
@@ -0,0 +1,14 @@
+// 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/files/file_path.h"
+#include "base/native_library.h"
+
+namespace gfx {
+
+bool InitializeGLBindingsOSMesaGL();
+base::NativeLibrary LoadLibrary(const char* filename);
+base::NativeLibrary LoadLibrary(const base::FilePath& filename);
+
+}  // namespace gfx