Add base::FeatureParam<> struct

components/ntp_snippets/features.cc

Index: components/ntp_snippets/features.cc
diff --git a/components/ntp_snippets/features.cc b/components/ntp_snippets/features.cc
index 985f5d6f0ea447ba67d0376d1d687869bd002af8..e8153e19aa1ce5284fa7f07c3f7d9ce13b450b36 100644
--- a/components/ntp_snippets/features.cc
+++ b/components/ntp_snippets/features.cc
@@ -9,7 +9,6 @@
 #include "base/time/clock.h"
 #include "components/ntp_snippets/category_rankers/click_based_category_ranker.h"
 #include "components/ntp_snippets/category_rankers/constant_category_ranker.h"
-#include "components/variations/variations_associated_data.h"
 
 namespace ntp_snippets {
 
@@ -62,38 +61,20 @@ const base::Feature kRemoteSuggestionsEmulateM58FetchingSchedule{
     "RemoteSuggestionsEmulateM58FetchingSchedule",
     base::FEATURE_DISABLED_BY_DEFAULT};
 
-const char kCategoryRankerParameter[] = "category_ranker";
+constexpr base::FeatureParam<CategoryRankerChoice>::Option
+    kCategoryRankerParameterOptions[] = {
+        {CategoryRankerChoice::CONSTANT, kCategoryRankerConstantRanker},
+        {CategoryRankerChoice::CLICK_BASED, kCategoryRankerClickBasedRanker}};
+constexpr base::FeatureParam<CategoryRankerChoice> kCategoryRankerParameter{
+    &kCategoryRanker, "category_ranker", CategoryRankerChoice::CONSTANT,
+    &kCategoryRankerParameterOptions};
 const char kCategoryRankerConstantRanker[] = "constant";
 const char kCategoryRankerClickBasedRanker[] = "click_based";
 
-CategoryRankerChoice GetSelectedCategoryRanker() {
-  std::string category_ranker_value =
-      variations::GetVariationParamValueByFeature(kCategoryRanker,
-                                                  kCategoryRankerParameter);
-
-  if (category_ranker_value.empty()) {
-    // TODO(crbug.com/735066): Remove the experiment configurations from
-    // fieldtrial_testing_config.json when enabling ClickBasedRanker by default.
-
-    // Default, Enabled or Disabled.
-    return CategoryRankerChoice::CONSTANT;
-  }
-  if (category_ranker_value == kCategoryRankerConstantRanker) {
-    return CategoryRankerChoice::CONSTANT;
-  }
-  if (category_ranker_value == kCategoryRankerClickBasedRanker) {
-    return CategoryRankerChoice::CLICK_BASED;
-  }
-
-  LOG(DFATAL) << "The " << kCategoryRankerParameter << " parameter value is '"
-              << category_ranker_value << "'";
-  return CategoryRankerChoice::CONSTANT;
-}
-
 std::unique_ptr<CategoryRanker> BuildSelectedCategoryRanker(
     PrefService* pref_service,
     std::unique_ptr<base::Clock> clock) {
-  CategoryRankerChoice choice = ntp_snippets::GetSelectedCategoryRanker();
+  CategoryRankerChoice choice = kCategoryRankerParameter.Get();
   switch (choice) {
     case CategoryRankerChoice::CONSTANT:
       return base::MakeUnique<ConstantCategoryRanker>();
@@ -107,34 +88,21 @@ std::unique_ptr<CategoryRanker> BuildSelectedCategoryRanker(
 const base::Feature kCategoryOrder{"ContentSuggestionsCategoryOrder",
                                    base::FEATURE_DISABLED_BY_DEFAULT};
 
-const char kCategoryOrderParameter[] = "category_order";
+constexpr base::FeatureParam<CategoryOrderChoice>::Option
+    kCategoryOrderParameterOptions[] = {
+        {CategoryOrderChoice::GENERAL, kCategoryOrderGeneral},
+        {CategoryOrderChoice::EMERGING_MARKETS_ORIENTED,
+         kCategoryOrderEmergingMarketsOriented}};
+const base::FeatureParam<CategoryOrderChoice> kCategoryOrderParameter{
+    &kCategoryOrder, "category_order", CategoryOrderChoice::GENERAL,
+    &kCategoryOrderParameterOptions};
+
 const char kCategoryOrderGeneral[] = "general";
 const char kCategoryOrderEmergingMarketsOriented[] =
     "emerging_markets_oriented";
 
 CategoryOrderChoice GetSelectedCategoryOrder() {
-  if (!base::FeatureList::IsEnabled(kCategoryOrder)) {
-    return CategoryOrderChoice::GENERAL;
-  }
-
-  std::string category_order_value =
-      variations::GetVariationParamValueByFeature(kCategoryOrder,
-                                                  kCategoryOrderParameter);
-
-  if (category_order_value.empty()) {
-    // Enabled with no parameters.
-    return CategoryOrderChoice::GENERAL;
-  }
-  if (category_order_value == kCategoryOrderGeneral) {
-    return CategoryOrderChoice::GENERAL;
-  }
-  if (category_order_value == kCategoryOrderEmergingMarketsOriented) {
-    return CategoryOrderChoice::EMERGING_MARKETS_ORIENTED;
-  }
-
-  LOG(DFATAL) << "The " << kCategoryOrderParameter << " parameter value is '"
-              << category_order_value << "'";
-  return CategoryOrderChoice::GENERAL;
+  return kCategoryOrderParameter.Get();
 }
 
 const base::Feature kNotificationsFeature = {"ContentSuggestionsNotifications",