[webnfc] Add WebNFC feature 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 834e0e99fac9137b2d5881dd3e3e48c899595b93..b05a477b7a2dff65903eb0688190f742555b0c6a 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -2730,6 +2730,12 @@ const FeatureEntry kFeatureEntries[] = {
      flag_descriptions::kColorCorrectRenderingDescription, kOsAll,
      MULTI_VALUE_TYPE(kColorCorrectRenderingChoices)},
 
+#if defined(OS_ANDROID)
+    {"enable-webnfc", flag_descriptions::kEnableWebNfcName,
+     flag_descriptions::kEnableWebNfcDescription, kOsAndroid,
+     FEATURE_VALUE_TYPE(features::kWebNfc)},
+#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.