Files required by a service now listed in manifest.

content/public/common/content_descriptor_keys.cc

Index: content/public/common/content_descriptor_keys.cc
diff --git a/content/public/common/content_descriptor_keys.cc b/content/public/common/content_descriptor_keys.cc
new file mode 100644
index 0000000000000000000000000000000000000000..25cf72e4b2c0b008c2dc7e5f2b4fda3e33c57135
--- /dev/null
+++ b/content/public/common/content_descriptor_keys.cc
@@ -0,0 +1,17 @@
+// Copyright 2017 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 "content/public/common/content_descriptor_keys.h"
+
+namespace content {
+
+const char kV8NativesDataDescriptor[] = "v8_natives_data";
+
+const char kV8SnapshotDataDescriptor[] = "v8_snapshot_data";
+
+const char kV8Snapshot32DataDescriptor[] = "v8_snapshot_32_data";
+
+const char kV8Snapshot64DataDescriptor[] = "v8_snapshot_64_data";
+
+}  // namespace content