Don't make classes derive from ChildProcessHost, and instead have them use it through composition...

content/browser/utility_process_host.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 CONTENT_BROWSER_UTILITY_PROCESS_HOST_H_
 #define CONTENT_BROWSER_UTILITY_PROCESS_HOST_H_
 #pragma once
 
 #include <string>
 #include <vector>
@@ skipping 66 matching lines @@
  private:
   // Starts a process if necessary.  Returns true if it succeeded or a process
   // has already been started via StartBatchMode().
   bool StartProcess();
 
   // IPC messages:
   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
 
   // BrowserChildProcessHost:
   virtual void OnProcessCrashed(int exit_code) OVERRIDE;
-  virtual bool CanShutdown() OVERRIDE;
 
   // A pointer to our client interface, who will be informed of progress.
   scoped_refptr<Client> client_;
   content::BrowserThread::ID client_thread_id_;
   // True when running in batch mode, i.e., StartBatchMode() has been called
   // and the utility process will run until EndBatchMode().
   bool is_batch_mode_;
 
   // Allows a directory to be opened through the sandbox, in case it's needed by
   // the operation.
   FilePath exposed_dir_;
 
   // Whether to pass switches::kNoSandbox to the child.
   bool no_sandbox_;
 
   // Flags defined in ChildProcessHost with which to start the process.
   int child_flags_;
 
   base::environment_vector env_;
 
   bool started_;
 
   DISALLOW_COPY_AND_ASSIGN(UtilityProcessHost);
 };
 
 #endif  // CONTENT_BROWSER_UTILITY_PROCESS_HOST_H_