Split mojo_system dylib into public and private

mojo/system/system_impl_export.h

Index: mojo/system/system_impl_export.h
diff --git a/mojo/system/system_impl_export.h b/mojo/system/system_impl_export.h
new file mode 100644
index 0000000000000000000000000000000000000000..a35eacfe5a5661e77031fa965dee43c5dcad3492
--- /dev/null
+++ b/mojo/system/system_impl_export.h
@@ -0,0 +1,29 @@
+// Copyright 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.
+
+#ifndef MOJO_SYSTEM_SYSTEM_IMPL_EXPORT_H_
+#define MOJO_SYSTEM_SYSTEM_IMPL_EXPORT_H_
+
+#if defined(COMPONENT_BUILD)
+#if defined(WIN32)
+
+#if defined(MOJO_SYSTEM_IMPL_IMPLEMENTATION)
+#define MOJO_SYSTEM_IMPL_EXPORT __declspec(dllexport)
+#else
+#define MOJO_SYSTEM_IMPL_EXPORT __declspec(dllimport)
+#endif  // defined(MOJO_SYSTEM_IMPL_IMPLEMENTATION)
+
+#else  // defined(WIN32)
+#if defined(MOJO_SYSTEM_IMPL_IMPLEMENTATION)
+#define MOJO_SYSTEM_IMPL_EXPORT __attribute__((visibility("default")))
+#else
+#define MOJO_SYSTEM_IMPL_EXPORT
+#endif
+#endif
+
+#else  // defined(COMPONENT_BUILD)
+#define MOJO_SYSTEM_IMPL_EXPORT
+#endif
+
+#endif  // MOJO_SYSTEM_SYSTEM_IMPL_EXPORT_H_