Add other variations (with ids) for NTPSnippets to chrome://flags

components/flags_ui/feature_entry.h

 // 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.
 
 #ifndef COMPONENTS_FLAGS_UI_FEATURE_ENTRY_H_
 #define COMPONENTS_FLAGS_UI_FEATURE_ENTRY_H_
 
 #include <string>
 
 #include "base/strings/string16.h"
@@ skipping 81 matching lines @@
   struct FeatureVariation {
     // Text that denotes the variation in chrome://flags. For each variation,
     // the user is shown an option labeled "Enabled <description_text>" (with
     // the exception of the first option labeled "Enabled" to make clear it is
     // the default one). No need for description_id, chrome://flags should not
     // get translated. The other parts here use ids for historical reasons and
     // can realistically also be moved to direct description_texts.
     const char* description_text;
     const FeatureParam* params;
     int num_params;
+    // A variation id number in the format of
+    // VariationsHttpHeaderProvider::SetDefaultVariationIds or an empty string
+    // if you do not need to set any variation_id for this feature variation.

[Alexei Svitkine (slow), 2016/07/27 15:04:18]

Why empty string and not nullptr?

[jkrcal, 2016/07/27 17:12:43]

Done.
(It was std::string originally, I did not notice the discrepancy when I fixed it
to char*)

+    const char* variation_id;
   };
 
   // The internal name of the feature entry. This is never shown to the user.
   // It _is_ however stored in the prefs file, so you shouldn't change the
   // name of existing flags.
   const char* internal_name;
 
   // String id of the message containing the feature's name.
   int visible_name_id;
 
@@ skipping 67 matching lines @@
 
 // Separator used for multi values. Multi values are represented in prefs as
 // name-of-experiment + kMultiSeparator + selected_index.
 extern const char kMultiSeparator[];
 
 }  // namespace
 
 }  // namespace flag_ui
 
 #endif  // COMPONENTS_FLAGS_UI_FEATURE_ENTRY_H_