ExtensionsServiceBackend::GarbageCollectionExtensions() makes a local copy of install_directory_

chrome/browser/extensions/extensions_service.cc

 // Copyright (c) 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.
 
 #include "chrome/browser/extensions/extensions_service.h"
 
 #include "app/l10n_util.h"
 #include "base/command_line.h"
 #include "base/crypto/signature_verifier.h"
 #include "base/file_util.h"
@@ skipping 541 matching lines @@
 }
 
 void ExtensionsServiceBackend::GarbageCollectExtensions(
     scoped_refptr<ExtensionsService> frontend) {
   frontend_ = frontend;
   alert_on_error_ = false;
 
   // Nothing to clean up if it doesn't exist.
   if (!file_util::DirectoryExists(install_directory_))
     return;
-
-  file_util::AbsolutePath(&install_directory_);
+  
+  FilePath install_directory_absolute(install_directory_);
+  file_util::AbsolutePath(&install_directory_absolute);
 
   LOG(INFO) << "Loading installed extensions...";
 
   // Find all child directories in the install directory and load their
   // manifests. Post errors and results to the frontend.
-  file_util::FileEnumerator enumerator(install_directory_,
+  file_util::FileEnumerator enumerator(install_directory_absolute,
                                        false,  // Not recursive.
                                        file_util::FileEnumerator::DIRECTORIES);
   FilePath extension_path;
   for (extension_path = enumerator.Next(); !extension_path.value().empty();
        extension_path = enumerator.Next()) {
     std::string extension_id = WideToASCII(
         extension_path.BaseName().ToWStringHack());
 
     // The utility process might be in the middle of unpacking an extension, so
     // ignore the temp unpacking directory.
@@ skipping 799 matching lines @@
   Extension::InstallType install_type =
       CompareToInstalledVersion(id, version->GetString(), &current_version);
 
   if (install_type == Extension::DOWNGRADE)
     return false;
 
   return (install_type == Extension::UPGRADE ||
           install_type == Extension::NEW_INSTALL ||
           NeedsReinstall(id, current_version));
 }