Remove support for the keygen tag

chrome/browser/chrome_content_browser_client.h

 // Copyright (c) 2012 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.
 
 #ifndef CHROME_BROWSER_CHROME_CONTENT_BROWSER_CLIENT_H_
 #define CHROME_BROWSER_CHROME_CONTENT_BROWSER_CLIENT_H_
 
 #include <stddef.h>
 
 #include <memory>
@@ skipping 143 matching lines @@
   bool AllowWorkerIndexedDB(
       const GURL& url,
       const base::string16& name,
       content::ResourceContext* context,
       const std::vector<std::pair<int, int>>& render_frames) override;
 #if BUILDFLAG(ENABLE_WEBRTC)
   bool AllowWebRTCIdentityCache(const GURL& url,
                                 const GURL& first_party_url,
                                 content::ResourceContext* context) override;
 #endif  // BUILDFLAG(ENABLE_WEBRTC)
-  bool AllowKeygen(const GURL& url, content::ResourceContext* context) override;
   AllowWebBluetoothResult AllowWebBluetooth(
       content::BrowserContext* browser_context,
       const url::Origin& requesting_origin,
       const url::Origin& embedding_origin) override;
   std::string GetWebBluetoothBlocklist() override;
   net::URLRequestContext* OverrideRequestContextForURL(
       const GURL& url,
       content::ResourceContext* context) override;
   content::QuotaPermissionContext* CreateQuotaPermissionContext() override;
   std::unique_ptr<storage::QuotaEvictionPolicy>
@@ skipping 194 matching lines @@
   // Vector of additional ChromeContentBrowserClientParts.
   // Parts are deleted in the reverse order they are added.
   std::vector<ChromeContentBrowserClientParts*> extra_parts_;
 
   base::WeakPtrFactory<ChromeContentBrowserClient> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ChromeContentBrowserClient);
 };
 
 #endif  // CHROME_BROWSER_CHROME_CONTENT_BROWSER_CLIENT_H_