Delete the NTPPreferAmpUrls feature flag.

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 66a330610ac6671d7dfdadffbb133f040c542e53..dbc0f94cf638e2ef39999294cd279ddd475dd532 100644
--- a/components/ntp_snippets/features.cc
+++ b/components/ntp_snippets/features.cc
@@ -23,7 +23,6 @@ const base::Feature*(kAllFeatures[]) = {&kArticleSuggestionsFeature,
                                         &kIncreasedVisibility,
                                         &kNotificationsFeature,
                                         &kPhysicalWebPageSuggestionsFeature,
-                                        &kPreferAmpUrlsFeature,
                                         &kPublisherFaviconsFromNewServerFeature,
                                         &kRecentOfflineTabSuggestionsFeature,
                                         nullptr};
@@ -49,9 +48,6 @@ const base::Feature kForeignSessionsSuggestionsFeature{
 const base::Feature kContentSuggestionsPushFeature{
     "ContentSuggestionsPush", 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};