AppShell support for Mac.

extensions/shell/app/shell_main_mac.h

Index: extensions/shell/app/shell_main_mac.h
diff --git a/extensions/shell/app/shell_main_mac.h b/extensions/shell/app/shell_main_mac.h
new file mode 100644
index 0000000000000000000000000000000000000000..457806fa488e9d1fc1d3b5e1a34a2defda2caf96
--- /dev/null
+++ b/extensions/shell/app/shell_main_mac.h
@@ -0,0 +1,16 @@
+// Copyright 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.
+
+#ifndef EXTENSIONS_SHELL_APP_SHELL_MAIN_MAC_H_
+#define EXTENSIONS_SHELL_APP_SHELL_MAIN_MAC_H_
+
+#include "build/build_config.h"
+
+extern "C" {
+__attribute__((visibility("default"))) int ContentMain(int argc,
+                                                       const char** argv);
+}  // extern "C"
+
+#endif  // EXTENSIONS_SHELL_APP_SHELL_MAIN_MAC_H_
+