Implement the V2 sandbox in the process launcher.

content/public/common/content_features.cc

 // Copyright 2015 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 "build/build_config.h"
 #include "content/public/common/content_features.h"
 
 namespace features {
 
 // All features in alphabetical order.
@@ skipping 373 matching lines @@
 const base::Feature kWebNfc{"WebNFC", base::FEATURE_DISABLED_BY_DEFAULT};
 #endif
 
 #if defined(OS_WIN)
 // Emergency "off switch" for new Windows sandbox security mitigation,
 // sandbox::MITIGATION_EXTENSION_POINT_DISABLE.
 const base::Feature kWinSboxDisableExtensionPoints{
     "WinSboxDisableExtensionPoint", base::FEATURE_ENABLED_BY_DEFAULT};
 #endif
 
+#if defined(OS_MACOSX)
+// The V2 sandbox on MacOS removes the unsandboed warmup phase and sandboxes the
+// entire life of the process.
+const base::Feature kMacV2Sandbox{"MacV2Sandbox",
+                                  base::FEATURE_DISABLED_BY_DEFAULT};
+#endif  // defined(OS_MACOSX)
+
 }  // namespace features