[webnfc] Add WebNFC feature flag

chrome/browser/flag_descriptions.cc

Index: chrome/browser/flag_descriptions.cc
diff --git a/chrome/browser/flag_descriptions.cc b/chrome/browser/flag_descriptions.cc
index e42bd86f598bf20586231b4f56d7a5905b3c457b..d1ba3edf7ee6588d49fd65903c13dc510d08108e 100644
--- a/chrome/browser/flag_descriptions.cc
+++ b/chrome/browser/flag_descriptions.cc
@@ -3027,6 +3027,10 @@ const char kEnableCopylessPasteDescription[] =
     "to enter into the search bar. The data is indexed locally, and never sent "
     "to the server. It's disabled in incognito mode.";
 
+const char kEnableWebNfcName[] = "WebNFC";
+
+const char kEnableWebNfcDescription[] = "Enable WebNFC support.";
+
 #endif  // defined(OS_ANDROID)
 
 }  // namespace flag_descriptions