[webnfc] Add WebNFC feature flag

content/public/android/java/src/org/chromium/content/browser/ContentFeatureList.java

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.content.browser;
 
 import org.chromium.base.annotations.JNINamespace;
 import org.chromium.base.annotations.MainDex;
 
 /**
@@ skipping 13 matching lines @@
      *
      * @param featureName The name of the feature to query.
      * @return Whether the feature is enabled or not.
      */
     public static boolean isEnabled(String featureName) {
         return nativeIsEnabled(featureName);
     }
 
     // Alphabetical:
     public static final String REQUEST_UNBUFFERED_DISPATCH = "RequestUnbufferedDispatch";
+    public static final String WEB_NFC = "WebNFC";
 
     private static native boolean nativeIsEnabled(String featureName);
 }