[webnfc] Add WebNFC feature flag

chrome/browser/flag_descriptions.h

Index: chrome/browser/flag_descriptions.h
diff --git a/chrome/browser/flag_descriptions.h b/chrome/browser/flag_descriptions.h
index e271f36f97cfa896c83560f8a37aae708a6c0c33..4111736054bb91c055511898b74fac8e39d7314e 100644
--- a/chrome/browser/flag_descriptions.h
+++ b/chrome/browser/flag_descriptions.h
@@ -3287,6 +3287,12 @@ extern const char kEnableCopylessPasteName[];
 // Description of the flag that enables Copyless Paste.
 extern const char kEnableCopylessPasteDescription[];
 
+// Title for the flag to enable WebNFC.
+extern const char kEnableWebNfcName[];
+
+// Description for the flag to enable WebNFC.
+extern const char kEnableWebNfcDescription[];
+
 #endif  // defined(OS_ANDROID)
 
 }  // namespace flag_descriptions