Experimentally isolate OpenItemViaShell in a utility process.

chrome/common/chrome_utility_messages.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.
 
 // Multiply-included message file, so no include guard.
 
 #if defined(OS_WIN)
 #include <Windows.h>
 #endif  // defined(OS_WIN)
 
@@ skipping 73 matching lines @@
 IPC_MESSAGE_CONTROL0(ChromeUtilityMsg_StartupPing)
 
 #if defined(FULL_SAFE_BROWSING)
 // Tells the utility process to analyze a zip file for malicious download
 // protection.
 IPC_MESSAGE_CONTROL1(ChromeUtilityMsg_AnalyzeZipFileForDownloadProtection,
                      IPC::PlatformFileForTransit /* zip_file */)
 #endif
 
 #if defined(OS_WIN)
+IPC_MESSAGE_CONTROL1(ChromeUtilityMsg_OpenItemViaShell,
+                     base::FilePath /* full_path */)
+
 // A vector of filters, each being a Tuple2a display string (i.e. "Text Files")
 // and a filter pattern (i.e. "*.txt")..
 typedef std::vector<Tuple2<base::string16, base::string16> >
     GetOpenFileNameFilter;
 
 // Instructs the utility process to invoke GetOpenFileName. |owner| is the
 // parent of the modal dialog, |flags| are OFN_* flags. |filter| constrains the
 // user's file choices. |initial_directory| and |filename| select the directory
 // to be displayed and the file to be initially selected.
 //
@@ skipping 50 matching lines @@
     ChromeUtilityHostMsg_AnalyzeZipFileForDownloadProtection_Finished,
     safe_browsing::zip_analyzer::Results)
 #endif
 
 #if defined(OS_WIN)
 IPC_MESSAGE_CONTROL0(ChromeUtilityHostMsg_GetOpenFileName_Failed)
 IPC_MESSAGE_CONTROL2(ChromeUtilityHostMsg_GetOpenFileName_Result,
                      base::FilePath /* directory */,
                      std::vector<base::FilePath> /* filenames */)
 #endif  // defined(OS_WIN)