[Remote suggestions] Add a remote suggestions flag to choose the source

components/ntp_snippets/features.cc

 // 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 "components/ntp_snippets/features.h"
 
 #include "base/feature_list.h"
 #include "base/memory/ptr_util.h"
 #include "base/time/clock.h"
 #include "components/ntp_snippets/category_rankers/click_based_category_ranker.h"
@@ skipping 16 matching lines @@
 
 const base::Feature kOfflineBadgeFeature{
     "NTPOfflineBadge", base::FEATURE_ENABLED_BY_DEFAULT};
 
 const base::Feature kIncreasedVisibility{
     "NTPSnippetsIncreasedVisibility", base::FEATURE_ENABLED_BY_DEFAULT};
 
 const base::Feature kPhysicalWebPageSuggestionsFeature{
     "NTPPhysicalWebPageSuggestions", base::FEATURE_DISABLED_BY_DEFAULT};
 
-const base::Feature kContentSuggestionsSource{
-    "NTPSnippets", base::FEATURE_ENABLED_BY_DEFAULT};
-
 const base::Feature kForeignSessionsSuggestionsFeature{
     "NTPForeignSessionsSuggestions", base::FEATURE_DISABLED_BY_DEFAULT};
 
 const base::Feature kPreferAmpUrlsFeature{"NTPPreferAmpUrls",
                                           base::FEATURE_ENABLED_BY_DEFAULT};
 
 const base::Feature kCategoryRanker{"ContentSuggestionsCategoryRanker",
                                     base::FEATURE_ENABLED_BY_DEFAULT};
 
 const char kCategoryRankerParameter[] = "category_ranker";
@@ skipping 62 matching lines @@
   if (category_order_value == kCategoryOrderEmergingMarketsOriented) {
     return CategoryOrderChoice::EMERGING_MARKETS_ORIENTED;
   }
 
   LOG(DFATAL) << "The " << kCategoryOrderParameter << " parameter value is '"
               << category_order_value << "'";
   return CategoryOrderChoice::GENERAL;
 }
 
 }  // namespace ntp_snippets