Update checks of multi-installs now use the proper app guid....

chrome/installer/util/helper.cc

-// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Copyright (c) 2011 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/installer/util/helper.h"
 
 #include "base/command_line.h"
 #include "base/file_path.h"
 #include "base/logging.h"
 #include "base/path_service.h"
 #include "base/win/registry.h"
 #include "chrome/installer/util/browser_distribution.h"
 #include "chrome/installer/util/install_util.h"
 #include "chrome/installer/util/master_preferences.h"
+#include "chrome/installer/util/package_properties.h"
 
 using base::win::RegKey;
 
 namespace {
 
 FilePath GetChromeInstallBasePath(bool system,
                                   BrowserDistribution* distribution,
                                   const wchar_t* sub_path) {
   FilePath install_path;
   if (system) {
@@ skipping 94 matching lines @@
 
   // Return Chrome's installation folder.
   VLOG(1) << "Chrome Frame will be installed as 'multi'";
   const MasterPreferences& prefs = MasterPreferences::ForCurrentProcess();
   BrowserDistribution* chrome =
       BrowserDistribution::GetSpecificDistribution(
           BrowserDistribution::CHROME_BROWSER, prefs);
   return GetChromeInstallPath(system_install, chrome);
 }
 
+std::wstring GetAppGuidForUpdates(bool system_install) {
+  BrowserDistribution* dist = BrowserDistribution::GetDistribution();
+
+  // If we're part of a multi-install, we need to poll using the multi-installer
+  // package's app guid rather than the browser's or Chrome Frame's app guid.
+  return IsInstalledAsMulti(system_install, dist) ?
+      ActivePackageProperties().GetAppGuid() :
+      dist->GetAppGuid();
+}
+
 }  // namespace installer.