Add Ignition to about:flags.

gin/gin_features.cc

Index: gin/gin_features.cc
diff --git a/gin/gin_features.cc b/gin/gin_features.cc
new file mode 100644
index 0000000000000000000000000000000000000000..9bb2130a015c61b1bf2c1bf98514fa1f538ce0c9
--- /dev/null
+++ b/gin/gin_features.cc
@@ -0,0 +1,14 @@
+// Copyright 2016 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 "gin/public/gin_features.h"
+
+namespace features {
+
+// Enables or disables the experimental V8 Ignition interpreter.
+const base::Feature kV8Ignition {
+  "V8Ignition", base::FEATURE_DISABLED_BY_DEFAULT
+};
+
+}  // namespace features