Use different product IO for SxS in mini installer....

chrome/installer/mini_installer/mini_installer.cc

 // Copyright (c) 2006-2009 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.
 
 // mini_installer.exe is the first exe that is run when chrome is being
 // installed or upgraded. It is designed to be extremely small (~5KB with no
 // extra resources linked) and it has two main jobs:
 //   1) unpack the resources (possibly decompressing some)
 //   2) run the real installer (setup.exe) with appropiate flags.
 //
@@ skipping 132 matching lines @@
   }
   return false;
 }
 
 // This function sets the flag in registry to indicate that Google Update
 // should try full installer next time. If the current installer works, this
 // flag is cleared by setup.exe at the end of install.
 void SetFullInstallerFlag(HKEY root_key) {
   HKEY key;
   wchar_t ap_registry_key[128];
+  const wchar_t* app_guid = google_update::kAppGuid;
+
+  int args_num;
+  wchar_t* cmd_line = ::GetCommandLine();
+  wchar_t** args = ::CommandLineToArgvW(cmd_line, &args_num);
+  for (int i = 1; i < args_num; ++i) {
+    if (0 == ::lstrcmpi(args[i], L"--chrome-sxs"))
+      app_guid = google_update::kSxSAppGuid;
+  }
+
   if (!SafeStrCopy(ap_registry_key, _countof(ap_registry_key),
                    kApRegistryKeyBase) ||
       !SafeStrCat(ap_registry_key, _countof(ap_registry_key),
-                  google_update::kAppGuid)) {
+                  app_guid)) {
     return;
   }
   if (::RegOpenKeyEx(root_key, ap_registry_key, NULL,
                      KEY_READ | KEY_SET_VALUE, &key) != ERROR_SUCCESS)
     return;
 
   wchar_t value[128];
   size_t size = _countof(value);
   size_t buf_size = size;
   LONG ret = ::RegQueryValueEx(key, kApRegistryValueName, NULL, NULL,
@@ skipping 372 matching lines @@
 
   return exit_code;
 }
 }  // namespace mini_installer
 
 
 int MainEntryPoint() {
   int result = mini_installer::WMain(::GetModuleHandle(NULL));
   ::ExitProcess(result);
 }