Add base::FeatureParam<> struct

components/ntp_snippets/remote/remote_suggestions_fetcher.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/remote/remote_suggestions_fetcher.h"
 
 #include "components/ntp_snippets/features.h"
 #include "components/ntp_snippets/ntp_snippets_constants.h"
 #include "components/strings/grit/components_strings.h"
 #include "components/variations/variations_associated_data.h"
 #include "ui/base/l10n/l10n_util.h"
 
 namespace ntp_snippets {
 
 namespace {
 
 // Variation parameter for chrome-content-suggestions backend.
-const char kContentSuggestionsBackend[] = "content_suggestions_backend";
+constexpr base::FeatureParam<std::string> kContentSuggestionsBackend{
+    &kArticleSuggestionsFeature, "content_suggestions_backend", ""};
 
 }  // namespace
 
 GURL GetFetchEndpoint(version_info::Channel channel) {
-  std::string endpoint = variations::GetVariationParamValueByFeature(
-      ntp_snippets::kArticleSuggestionsFeature, kContentSuggestionsBackend);
+  std::string endpoint = kContentSuggestionsBackend.Get();
   if (!endpoint.empty()) {
     return GURL{endpoint};
   }
 
   switch (channel) {
     case version_info::Channel::STABLE:
     case version_info::Channel::BETA:
       return GURL{kContentSuggestionsServer};
 
     case version_info::Channel::DEV:
     case version_info::Channel::CANARY:
     case version_info::Channel::UNKNOWN:
       return GURL{kContentSuggestionsStagingServer};
   }
   NOTREACHED();
   return GURL{kContentSuggestionsStagingServer};
 }
 
 RemoteSuggestionsFetcher::~RemoteSuggestionsFetcher() = default;
 
 }  // namespace ntp_snippets