The first run sentinel does not get created for system install...

chrome/browser/first_run.cc

 // Copyright (c) 2006-2008 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 <atlbase.h>
 #include <atlcom.h>
 #include <windows.h>
 #include <shlobj.h>
 
 #include <sstream>
@@ skipping 31 matching lines @@
 
 #include "google_update_idl.h"
 
 namespace {
 
 // The kSentinelFile file absence will tell us it is a first run.
 const wchar_t kSentinelFile[] = L"First Run";
 
 // Gives the full path to the sentinel file. The file might not exist.
 bool GetFirstRunSentinelFilePath(std::wstring* path) {
+  std::wstring exe_path;
+  if (!PathService::Get(base::DIR_EXE, &exe_path))
+    return false;
+
   std::wstring first_run_sentinel;
-  if (!PathService::Get(base::DIR_EXE, &first_run_sentinel))
-    return false;
+  if (InstallUtil::IsPerUserInstall(exe_path.c_str())) {
+    first_run_sentinel = exe_path;
+  } else {
+    if (!PathService::Get(chrome::DIR_USER_DATA, &first_run_sentinel))
+      return false;
+  }
+
   file_util::AppendToPath(&first_run_sentinel, kSentinelFile);
   *path = first_run_sentinel;
   return true;
 }
 
 bool GetNewerChromeFile(std::wstring* path) {
   if (!PathService::Get(base::DIR_EXE, path))
     return false;
   file_util::AppendToPath(path, installer_util::kChromeNewExe);
   return true;
@@ skipping 460 matching lines @@
 bool FirstRun::SetShowWelcomePagePref() {
   PrefService* local_state = g_browser_process->local_state();
   if (!local_state)
     return false;
   if (!local_state->IsPrefRegistered(prefs::kShouldShowWelcomePage)) {
     local_state->RegisterBooleanPref(prefs::kShouldShowWelcomePage, false);
     local_state->SetBoolean(prefs::kShouldShowWelcomePage, true);
   }
   return true;
 }