[NTP Snippets] Make a base::Feature instead of raw cmdline flag

chrome/browser/about_flags.cc

Index: chrome/browser/about_flags.cc
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index 03a8170504b43c935fb2b0b35d9634ed3506995c..c25986e1dcad49538dd66817a70d326cff2d3426 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -2168,6 +2168,13 @@ const FeatureEntry kFeatureEntries[] = {
       IDS_FLAGS_ENABLE_TOKEN_BINDING_DESCRIPTION,
       kOsAll,
       FEATURE_VALUE_TYPE(features::kTokenBinding)},
+#if defined(OS_ANDROID)
+    {"enable-ntp-snippets",
+     IDS_FLAGS_ENABLE_NTP_SNIPPETS_NAME,
+     IDS_FLAGS_ENABLE_NTP_SNIPPETS_DESCRIPTION,
+     kOsAndroid,
+     FEATURE_VALUE_TYPE(chrome::android::kNTPSnippetsFeature)},
+#endif
     // NOTE: Adding new command-line switches requires adding corresponding
     // entries to enum "LoginCustomFlags" in histograms.xml. See note in
     // histograms.xml and don't forget to run AboutFlagsHistogramTest unit test.