Experimentally isolate OpenItemViaShell in a utility process.

content/public/browser/utility_process_host.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_PUBLIC_BROWSER_UTILITY_PROCESS_HOST_H_
 #define CONTENT_PUBLIC_BROWSER_UTILITY_PROCESS_HOST_H_
 
 #include "base/environment.h"
 #include "base/process/launch.h"
 #include "base/threading/thread.h"
@@ skipping 16 matching lines @@
 // If you need multiple batches of work to be done in the 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 since this object is deleted synchronously but the
 // client notification is asynchronous.  See http://crbug.com/108871.
 class UtilityProcessHost : public IPC::Sender,
                            public base::SupportsWeakPtr<UtilityProcessHost> {
  public:
-  // Used to create a utility process.
+  // Used to create a utility process. |client| is optional. If supplied it will
+  // be notified of incoming messages from the utility process.
+  // |client_task_runner| is required if |client| is supplied and is the task
+  // runner upon which |client| will be invoked.
   CONTENT_EXPORT static UtilityProcessHost* Create(
       UtilityProcessHostClient* client,
       base::SequencedTaskRunner* client_task_runner);
 
   virtual ~UtilityProcessHost() {}
 
   // Starts utility process in batch mode. Caller must call EndBatchMode()
   // to finish the utility process.
   virtual bool StartBatchMode() = 0;
 
@@ skipping 19 matching lines @@
   virtual const ChildProcessData& GetData() = 0;
 
 #if defined(OS_POSIX)
   virtual void SetEnv(const base::EnvironmentMap& env) = 0;
 #endif
 };
 
 };  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_UTILITY_PROCESS_HOST_H_