Experimentally isolate OpenItemViaShell in a utility process.

content/browser/utility_process_host_impl.cc

Index: content/browser/utility_process_host_impl.cc
diff --git a/content/browser/utility_process_host_impl.cc b/content/browser/utility_process_host_impl.cc
index ddc41a74131328ef6f3bb83d0799d1341f52b2c2..a72d604c6b4adb5e20a76b1d3f5c4d98dd0b9596 100644
--- a/content/browser/utility_process_host_impl.cc
+++ b/content/browser/utility_process_host_impl.cc
@@ -267,15 +267,23 @@ bool UtilityProcessHostImpl::StartProcess() {
 }
 
 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,
@@ -283,6 +291,9 @@ void UtilityProcessHostImpl::OnProcessLaunchFailed() {
 }
 
 void UtilityProcessHostImpl::OnProcessCrashed(int exit_code) {
+  if (!client_)
+    return;
+
   client_task_runner_->PostTask(
       FROM_HERE,
       base::Bind(&UtilityProcessHostClient::OnProcessCrashed, client_.get(),