It suffices to just forward-declare DnsCertProvenanceChecker

chrome/browser/net/chrome_url_request_context.h

 // Copyright (c) 2011 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_NET_CHROME_URL_REQUEST_CONTEXT_H_
 #define CHROME_BROWSER_NET_CHROME_URL_REQUEST_CONTEXT_H_
 #pragma once
 
 #include <string>
 #include <vector>
@@ skipping 16 matching lines @@
 class ChromeURLDataManagerBackend;
 class ChromeURLRequestContextFactory;
 class IOThread;
 class PrefService;
 class Profile;
 class ProfileIOData;
 namespace base {
 class WaitableEvent;
 }
 namespace net {
-class DnsCertProvenanceChecker;
 class NetworkDelegate;
 }
 
 // Subclass of net::URLRequestContext which can be used to store extra
 // information for requests.
 //
 // All methods of this class must be called from the IO thread,
 // including the constructor and destructor.
 class ChromeURLRequestContext : public net::URLRequestContext {
  public:
@@ skipping 210 matching lines @@
 
   // NULL if not yet initialized. Otherwise, it is the net::URLRequestContext
   // instance that was lazilly created by GetURLRequestContext.
   // Access only from the IO thread.
   scoped_refptr<net::URLRequestContext> url_request_context_;
 
   DISALLOW_COPY_AND_ASSIGN(ChromeURLRequestContextGetter);
 };
 
 #endif  // CHROME_BROWSER_NET_CHROME_URL_REQUEST_CONTEXT_H_