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

chrome/service/service_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 CHROME_SERVICE_SERVICE_UTILITY_PROCESS_HOST_H_
 #define CHROME_SERVICE_SERVICE_UTILITY_PROCESS_HOST_H_
 #pragma once
 
 #include "build/build_config.h"
 
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/file_path.h"
 #include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/process.h"
 #include "base/task.h"
 #include "ipc/ipc_channel.h"
-#include "chrome/service/service_child_process_host.h"
+#include "content/public/common/child_process_host_delegate.h"
 #include "printing/pdf_render_settings.h"
 
+class ChildProcessHost;
+class CommandLine;
 class ScopedTempDir;
 
 namespace base {
 class MessageLoopProxy;
 }  // namespace base
 
 namespace printing {
 class Emf;
 struct PageRange;
 struct PrinterCapsAndDefaults;
 }  // namespace printing
 
 // Acts as the service-side host to a utility child process. A
 // utility process is a short-lived sandboxed process that is created to run
 // a specific task.
-class ServiceUtilityProcessHost : public ServiceChildProcessHost {
+class ServiceUtilityProcessHost : public content::ChildProcessHostDelegate {
  public:
   // Consumers of ServiceUtilityProcessHost must implement this interface to
   // get results back.  All functions are called on the thread passed along
   // to ServiceUtilityProcessHost.
   class Client : public base::RefCountedThreadSafe<Client> {
    public:
     Client() {}
 
     // Called when the child process died before a reply was receieved.
     virtual void OnChildDied() {}
@@ skipping 46 matching lines @@
   // Starts a process to get capabilities and defaults for the specified
   // printer. Used on Windows to isolate the service process from printer driver
   // crashes by executing this in a separate process. The process does not run
   // in a sandbox.
   bool StartGetPrinterCapsAndDefaults(const std::string& printer_name);
 
  protected:
   // Allows this method to be overridden for tests.
   virtual FilePath GetUtilityProcessCmd();
 
-  // ChildProcessHost implementation.
+  // ChildProcessHostDelegate implementation:
   virtual bool CanShutdown() OVERRIDE;
-  virtual void OnChildDied() OVERRIDE;
+  virtual void OnChildDisconnected() OVERRIDE;
+  virtual void ShutdownStarted() OVERRIDE;
+  virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
 
  private:
   // Starts a process.  Returns true iff it succeeded. |exposed_dir| is the
   // path to the exposed to the sandbox. This is ignored if |no_sandbox| is
   // true.
   bool StartProcess(bool no_sandbox, const FilePath& exposed_dir);
 
-  // IPC messages:
-  virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
-  // Called when at least one page in the specified PDF has been rendered
-  // successfully into metafile_path_;
+  // Launch the child process synchronously.
+  // TODO(sanjeevr): Determine whether we need to make the launch asynchronous.
+  // |exposed_dir| is the path to tbe exposed to the sandbox. This is ignored
+  // if |no_sandbox| is true.
+  bool Launch(CommandLine* cmd_line,
+              bool no_sandbox,
+              const FilePath& exposed_dir);
+
+  base::ProcessHandle handle() const { return handle_; }
+
+  // Messages handlers:
   void OnRenderPDFPagesToMetafileSucceeded(int highest_rendered_page_number);
-  // Called when PDF rendering failed.
   void OnRenderPDFPagesToMetafileFailed();
-  // Called when the printer capabilities and defaults have been
-  // retrieved successfully.
   void OnGetPrinterCapsAndDefaultsSucceeded(
       const std::string& printer_name,
       const printing::PrinterCapsAndDefaults& caps_and_defaults);
-  // Called when the printer capabilities and defaults could not be
-  // retrieved successfully.
   void OnGetPrinterCapsAndDefaultsFailed(const std::string& printer_name);
 
+  scoped_ptr<ChildProcessHost> child_process_host_;
+  base::ProcessHandle handle_;
   // A pointer to our client interface, who will be informed of progress.
   scoped_refptr<Client> client_;
   scoped_refptr<base::MessageLoopProxy> client_message_loop_proxy_;
   bool waiting_for_reply_;
   // The path to the temp file where the metafile will be written to.
   FilePath metafile_path_;
   // The temporary folder created for the metafile.
   scoped_ptr<ScopedTempDir> scratch_metafile_dir_;
 
   DISALLOW_COPY_AND_ASSIGN(ServiceUtilityProcessHost);
 };
 
 #endif  // CHROME_SERVICE_SERVICE_UTILITY_PROCESS_HOST_H_