Install CRX updates one at a time.

chrome/browser/extensions/extension_service_unittest.cc

 // 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/browser/extensions/extension_service_unittest.h"
 
 #include <algorithm>
 #include <set>
 #include <vector>
 
@@ skipping 647 matching lines @@
     FilePath path = temp_dir_.path();
     path = path.Append(in_path.BaseName());
     ASSERT_TRUE(file_util::CopyFile(in_path, path));
 
     int previous_enabled_extension_count =
         service_->extensions()->size();
     int previous_installed_extension_count =
         previous_enabled_extension_count +
         service_->disabled_extensions()->size();
 
-    service_->UpdateExtension(id, path, GURL());
+    service_->UpdateExtension(id, path, GURL(), NULL);
     loop_.RunAllPending();
 
     std::vector<std::string> errors = GetErrors();
     int error_count = errors.size();
     int enabled_extension_count =
         service_->extensions()->size();
     int installed_extension_count =
         enabled_extension_count + service_->disabled_extensions()->size();
 
     int expected_error_count = (expected_state == FAILED) ? 1 : 0;
@@ skipping 3121 matching lines @@
   ASSERT_FALSE(AddPendingSyncInstall());
 
   // Wait for the external source to install.
   WaitForCrxInstall(crx_path_, true);
   ASSERT_TRUE(IsCrxInstalled());
 
   // Now that the extension is installed, sync request should fail
   // because the extension is already installed.
   ASSERT_FALSE(AddPendingSyncInstall());
 }