Fix a crash bug on user script installation

chrome/browser/extensions/crx_installer.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/crx_installer.h"
 
 #include "app/l10n_util.h"
 #include "base/file_util.h"
 #include "base/scoped_temp_dir.h"
 #include "base/string_util.h"
@@ skipping 18 matching lines @@
 }
 
 void CrxInstaller::Start(const FilePath& crx_path,
                          const FilePath& install_directory,
                          Extension::Location install_source,
                          const std::string& expected_id,
                          bool delete_source,
                          bool allow_privilege_increase,
                          ExtensionsService* frontend,
                          ExtensionInstallUI* client) {
-  // Note: We don't keep a reference because this object manages its own
-  // lifetime.
-  CrxInstaller* installer = new CrxInstaller(crx_path, install_directory,
-                                             delete_source, frontend,
-                                             client);
+  // Note: This object manages its own lifetime.
+  scoped_refptr<CrxInstaller> installer(
+      new CrxInstaller(crx_path, install_directory, delete_source, frontend,
+                       client));
+
   installer->install_source_ = install_source;
   installer->expected_id_ = expected_id;
   installer->allow_privilege_increase_ = allow_privilege_increase;
 
   scoped_refptr<SandboxedExtensionUnpacker> unpacker(
       new SandboxedExtensionUnpacker(
           installer->source_file_,
           g_browser_process->resource_dispatcher_host(),
-          installer));
+          installer.get()));
 
   ChromeThread::PostTask(
       ChromeThread::FILE, FROM_HERE,
       NewRunnableMethod(
           unpacker.get(), &SandboxedExtensionUnpacker::Start));
 }
 
 void CrxInstaller::InstallUserScript(const FilePath& source_file,
                                      const GURL& original_url,
                                      const FilePath& install_directory,
                                      bool delete_source,
                                      ExtensionsService* frontend,
                                      ExtensionInstallUI* client) {
-  CrxInstaller* installer = new CrxInstaller(source_file, install_directory,
-                                             delete_source, frontend, client);
+  scoped_refptr<CrxInstaller> installer(
+      new CrxInstaller(source_file, install_directory, delete_source, frontend,
+                       client));
   installer->original_url_ = original_url;
 
   ChromeThread::PostTask(
       ChromeThread::FILE, FROM_HERE,
-      NewRunnableMethod(installer, &CrxInstaller::ConvertUserScriptOnFileThread));
+      NewRunnableMethod(installer.get(),
+                        &CrxInstaller::ConvertUserScriptOnFileThread));
 }
 
 CrxInstaller::CrxInstaller(const FilePath& source_file,
                            const FilePath& install_directory,
                            bool delete_source,
                            ExtensionsService* frontend,
                            ExtensionInstallUI* client)
     : source_file_(source_file),
       install_directory_(install_directory),
       install_source_(Extension::INTERNAL),
@@ skipping 260 matching lines @@
     client_->OnInstallSuccess(extension_.get());
 
   // Tell the frontend about the installation and hand off ownership of
   // extension_ to it.
   frontend_->OnExtensionInstalled(extension_.release(),
                                   allow_privilege_increase_);
 
   // We're done. We don't post any more tasks to ourselves so we are deleted
   // soon.
 }