Experimentally isolate OpenItemViaShell in a utility process.

content/browser/utility_process_host_impl.cc

 // 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.
 
 #include "content/browser/utility_process_host_impl.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
 #include "base/lazy_instance.h"
@@ skipping 250 matching lines @@
                                                     run_elevated_,
                                                     no_sandbox_, env_,
                                                     process_->GetHost()),
         cmd_line);
   }
 
   return true;
 }
 
 bool UtilityProcessHostImpl::OnMessageReceived(const IPC::Message& message) {
+  if (!client_)
+    return true;
+
   client_task_runner_->PostTask(
       FROM_HERE,
-      base::Bind(base::IgnoreResult(
-          &UtilityProcessHostClient::OnMessageReceived), client_.get(),
+      base::Bind(
+          base::IgnoreResult(&UtilityProcessHostClient::OnMessageReceived),
+          client_.get(),
           message));
+
   return true;
 }
 
 void UtilityProcessHostImpl::OnProcessLaunchFailed() {
+  if (!client_)
+    return;
+
   client_task_runner_->PostTask(
       FROM_HERE,
       base::Bind(&UtilityProcessHostClient::OnProcessLaunchFailed,
                  client_.get()));
 }
 
 void UtilityProcessHostImpl::OnProcessCrashed(int exit_code) {
+  if (!client_)
+    return;
+
   client_task_runner_->PostTask(
       FROM_HERE,
       base::Bind(&UtilityProcessHostClient::OnProcessCrashed, client_.get(),
             exit_code));
 }
 
 }  // namespace content