Do not launch rename process directly from system-level Chrome.

chrome/browser/first_run/upgrade_util_win.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 "chrome/browser/first_run/upgrade_util.h"
 
 #include <windows.h>
 #include <psapi.h>
 #include <shellapi.h>
 
@@ skipping 95 matching lines @@
     return false;
   return base::PathExists(new_chrome_exe);
 }
 
 bool SwapNewChromeExeIfPresent() {
   if (!IsUpdatePendingRestart())
     return false;
   base::FilePath cur_chrome_exe;
   if (!PathService::Get(base::FILE_EXE, &cur_chrome_exe))
     return false;
-  bool user_install = InstallUtil::IsPerUserInstall(cur_chrome_exe);
 
-  // Ask Google Update to elevate and rename if the current process is in a
-  // per-machine install. Failing that, fall back to the direct approach.
-  if (!user_install && InvokeGoogleUpdateForRename())
-    return true;
+  // If this is a system-level install, ask Google Update to launch an elevated
+  // process to rename Chrome executables.
+  if (!InstallUtil::IsPerUserInstall(cur_chrome_exe))
+    return InvokeGoogleUpdateForRename();
 
-  // Open up the registry key containing current version and rename information.
-  HKEY reg_root = user_install ? HKEY_CURRENT_USER : HKEY_LOCAL_MACHINE;
-  BrowserDistribution *dist = BrowserDistribution::GetDistribution();
+  // If this is a user-level install, directly launch a process to rename Chrome
+  // executables. Obtain the command to launch the process from the registry.
   base::win::RegKey key;
-  if (key.Open(reg_root, dist->GetVersionKey().c_str(),
+  if (key.Open(HKEY_CURRENT_USER,
+               BrowserDistribution::GetDistribution()->GetVersionKey().c_str(),
                KEY_QUERY_VALUE | KEY_WOW64_32KEY) == ERROR_SUCCESS) {
-    // First try to rename exe by launching rename command ourselves.
     std::wstring rename_cmd;
     if (key.ReadValue(google_update::kRegRenameCmdField,
                       &rename_cmd) == ERROR_SUCCESS) {
       base::LaunchOptions options;
       options.wait = true;
       options.start_hidden = true;
       base::Process process = base::LaunchProcess(rename_cmd, options);
       if (process.IsValid()) {
         DWORD exit_code;
         ::GetExitCodeProcess(process.Handle(), &exit_code);
@@ skipping 30 matching lines @@
     return false;
   // At this point the chrome.exe has been swapped with the new one.
   if (!RelaunchChromeBrowser(command_line)) {
     // The re-launch fails. Feel free to panic now.
     NOTREACHED();
   }
   return true;
 }
 
 }  // namespace upgrade_util