Create an API around UtilityProcessHost and use that from chrome.

content/browser/utility_process_host_impl.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 CONTENT_BROWSER_UTILITY_PROCESS_HOST_H_
 #define CONTENT_BROWSER_UTILITY_PROCESS_HOST_H_
 #pragma once
 
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
+#include "base/compiler_specific.h"
 #include "base/memory/ref_counted.h"
-#include "base/process_util.h"
 #include "base/memory/weak_ptr.h"
-#include "content/common/content_export.h"
 #include "content/public/browser/browser_child_process_host_delegate.h"
-#include "content/public/browser/browser_thread.h"
-#include "ipc/ipc_message.h"
+#include "content/public/browser/utility_process_host.h"
 
 class BrowserChildProcessHostImpl;
 
-// This class acts as the browser-side host to a utility child process.  A
-// utility process is a short-lived sandboxed process that is created to run
-// a specific task.  This class lives solely on the IO thread.
-// If you need a single method call in the sandbox, use StartFooBar(p).
-// If you need multiple batches of work to be done in the sandboxed process,
-// use StartBatchMode(), then multiple calls to StartFooBar(p),
-// then finish with EndBatchMode().
-//
-// Note: If your class keeps a ptr to an object of this type, grab a weak ptr to
-// avoid a use after free.  See http://crbug.com/108871.
-class CONTENT_EXPORT UtilityProcessHost
-    : public content::BrowserChildProcessHostDelegate,
-      public IPC::Message::Sender,
-      public base::SupportsWeakPtr<UtilityProcessHost> {
+class CONTENT_EXPORT UtilityProcessHostImpl
+    : public NON_EXPORTED_BASE(content::UtilityProcessHost),
+      public content::BrowserChildProcessHostDelegate {
  public:
-  // An interface to be implemented by consumers of the utility process to
-  // get results back.  All functions are called on the thread passed along
-  // to UtilityProcessHost.
-  class CONTENT_EXPORT Client : public base::RefCountedThreadSafe<Client> {
-   public:
-    Client();
+  UtilityProcessHostImpl(content::UtilityProcessHostClient* client,
+                         content::BrowserThread::ID client_thread_id);
+  virtual ~UtilityProcessHostImpl();
 
-    // Called when the process has crashed.
-    virtual void OnProcessCrashed(int exit_code);
-
-    // Allow the client to filter IPC messages.
-    virtual bool OnMessageReceived(const IPC::Message& message);
-
-   protected:
-    friend class base::RefCountedThreadSafe<Client>;
-
-    virtual ~Client();
-
-   private:
-    friend class UtilityProcessHost;
-
-    DISALLOW_COPY_AND_ASSIGN(Client);
-  };
-
-  UtilityProcessHost(Client* client,
-                     content::BrowserThread::ID client_thread_id);
-  virtual ~UtilityProcessHost();
-
-  // IPC::Message::Sender implementation:
+  // UtilityProcessHost implementation:
   virtual bool Send(IPC::Message* message) OVERRIDE;
-
-  // Starts utility process in batch mode. Caller must call EndBatchMode()
-  // to finish the utility process.
-  bool StartBatchMode();
-
-  // Ends the utility process. Must be called after StartBatchMode().
-  void EndBatchMode();
-
-  void set_exposed_dir(const FilePath& dir) { exposed_dir_ = dir; }
-  void set_no_sandbox(bool flag) { no_sandbox_ = flag; }
-  void set_child_flags(int flags) { child_flags_ = flags; }
-  void set_use_linux_zygote(bool flag) { use_linux_zygote_ = flag; }
+  virtual bool StartBatchMode() OVERRIDE;
+  virtual void EndBatchMode() OVERRIDE;
+  virtual void SetExposedDir(const FilePath& dir) OVERRIDE;
+  virtual void DisableSandbox() OVERRIDE;
+  virtual void EnableZygote() OVERRIDE;
 #if defined(OS_POSIX)
-  void set_env(const base::environment_vector& env) { env_ = env; }
+  virtual void SetEnv(const base::environment_vector& env) OVERRIDE;
 #endif
 
- protected:
-  // Allow these methods to be overridden for tests.
-  virtual FilePath GetUtilityProcessCmd();
+  void set_child_flags(int flags) { child_flags_ = flags; }
 
  private:
   // Starts a process if necessary.  Returns true if it succeeded or a process
   // has already been started via StartBatchMode().
   bool StartProcess();
 
   // BrowserChildProcessHost:
   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
   virtual void OnProcessCrashed(int exit_code) OVERRIDE;
 
   // A pointer to our client interface, who will be informed of progress.
-  scoped_refptr<Client> client_;
+  scoped_refptr<content::UtilityProcessHostClient> 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_;
 
-  // If the |no_sandbox_| flag is off, and we are on Linux, launch the
-  // utility process from the zygote. Defaults to false.
-  // Can only be used for tasks that do not require FS access.
+  // Launch the utility process from the zygote. Defaults to false.
   bool use_linux_zygote_;
 
   base::environment_vector env_;
 
   bool started_;
 
   scoped_ptr<BrowserChildProcessHostImpl> process_;
 
-  DISALLOW_COPY_AND_ASSIGN(UtilityProcessHost);
+  DISALLOW_COPY_AND_ASSIGN(UtilityProcessHostImpl);
 };
 
 #endif  // CONTENT_BROWSER_UTILITY_PROCESS_HOST_H_