Remove support for the keygen tag

chrome/android/java/src/org/chromium/chrome/browser/preferences/website/KeygenInfo.java

-// Copyright 2015 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.chrome.browser.preferences.website;
-
-/**
- * Keygen information for a given origin.
- */
-public class KeygenInfo extends PermissionInfo {
-    public KeygenInfo(String origin, String embedder, boolean isIncognito) {
-        super(origin, embedder, isIncognito);
-    }
-
-    protected int getNativePreferenceValue(String origin, String embedder, boolean isIncognito) {
-        return WebsitePreferenceBridge.nativeGetKeygenSettingForOrigin(
-                origin, embedder, isIncognito);
-    }
-
-    protected void setNativePreferenceValue(
-            String origin, String embedder, ContentSetting value, boolean isIncognito) {
-        WebsitePreferenceBridge.nativeSetKeygenSettingForOrigin(origin, value.toInt(), isIncognito);
-    }
-}