Invoke setup.exe to reenable updates when the update bubble is clicked.

chrome/installer/setup/setup_main.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/installer/setup/setup_main.h"
 
 #include <windows.h>
 #include <msi.h>
 #include <shellapi.h>
 #include <shlobj.h>
@@ skipping 1181 matching lines @@
       *exit_code = installer::CourgettePatchFiles(input_file,
                                                   patch_file,
                                                   output_file);
     } else if (patch_type_str == installer::kBsdiff) {
       *exit_code = installer::BsdiffPatchFiles(input_file,
                                                patch_file,
                                                output_file);
     } else {
       *exit_code = installer::PATCH_INVALID_ARGUMENTS;
     }
+  } else if (cmd_line.HasSwitch(installer::switches::kReenableAutoupdates)) {
+    // setup.exe has been asked to attempt to reenable updates for Chrome.
+    // Figure out whether we should do so for the multi binaries or the main
+    // Chrome product.
+    const ProductState* chrome_state = original_state.GetProductState(
+        installer_state->system_install(), BrowserDistribution::CHROME_BROWSER);
+
+    BrowserDistribution::Type dist_type = BrowserDistribution::CHROME_BROWSER;
+    if (chrome_state && chrome_state->is_multi_install())
+      dist_type = BrowserDistribution::CHROME_BINARIES;
+
+    BrowserDistribution* dist =
+        BrowserDistribution::GetSpecificDistribution(dist_type);
+    bool updates_enabled =
+        GoogleUpdateSettings::ReenableAutoupdatesForApp(dist->GetAppGuid());
+    *exit_code = updates_enabled ? installer::REENABLE_UPDATES_SUCCEEDED :
+                                   installer::REENABLE_UPDATES_FAILED;
   } else {
     handled = false;
   }
 
   return handled;
 }
 
 bool ShowRebootDialog() {
   // Get a token for this process.
   HANDLE token;
@@ skipping 605 matching lines @@
     // Note that we allow the status installer::UNINSTALL_REQUIRES_REBOOT
     // to pass through, since this is only returned on uninstall which is
     // never invoked directly by Google Update.
     return_code = InstallUtil::GetInstallReturnCode(install_status);
   }
 
   VLOG(1) << "Installation complete, returning: " << return_code;
 
   return return_code;
 }