Attempt the elevated path for the rename dance first for per-machine installs.

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 90 matching lines @@
 }
 
 bool IsUpdatePendingRestart() {
   base::FilePath new_chrome_exe;
   if (!GetNewerChromeFile(&new_chrome_exe))
     return false;
   return base::PathExists(new_chrome_exe);
 }
 
 bool SwapNewChromeExeIfPresent() {
-  base::FilePath new_chrome_exe;
-  if (!GetNewerChromeFile(&new_chrome_exe))
-    return false;
-  if (!base::PathExists(new_chrome_exe))
+  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;
 
   // Open up the registry key containing current version and rename information.
-  bool user_install = InstallUtil::IsPerUserInstall(cur_chrome_exe);
   HKEY reg_root = user_install ? HKEY_CURRENT_USER : HKEY_LOCAL_MACHINE;
   BrowserDistribution *dist = BrowserDistribution::GetDistribution();
   base::win::RegKey key;
   if (key.Open(reg_root, dist->GetVersionKey().c_str(),
-               KEY_QUERY_VALUE) == ERROR_SUCCESS) {
+               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);
         if (exit_code == installer::RENAME_SUCCESSFUL)
           return true;
       }
     }
   }
 
-  // Rename didn't work so try to rename by calling Google Update
-  return InvokeGoogleUpdateForRename();
+  return false;
 }
 
 bool IsRunningOldChrome() {
   // This figures out the actual file name that the section containing the
   // mapped exe refers to. This is used instead of GetModuleFileName because the
   // .exe may have been renamed out from under us while we've been running which
   // GetModuleFileName won't notice.
   wchar_t mapped_file_name[MAX_PATH * 2] = {};
 
   if (!::GetMappedFileName(::GetCurrentProcess(),
@@ skipping 13 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