chromeos: Fix inappropriate NULL check in AddDriveMountPoint

chrome/browser/chromeos/extensions/file_browser_private_api.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/browser/chromeos/extensions/file_browser_private_api.h"
 
 #include <sys/stat.h>
 #include <sys/statvfs.h>
 #include <sys/types.h>
 #include <utime.h>
@@ skipping 224 matching lines @@
   const base::FilePath mount_point = drive::util::GetDriveMountPointPath();
   // Grant R/W permissions to drive 'folder'. File API layer still
   // expects this to be satisfied.
   GrantFilePermissionsToHost(render_view_host,
                              mount_point,
                              file_handler_util::GetReadWritePermissions());
 
   // Grant R/W permission for tmp and pinned cache folder.
   drive::DriveSystemService* system_service =
       drive::DriveSystemServiceFactory::GetForProfile(profile);
+  drive::DriveCache* cache = system_service ? system_service->cache() : NULL;
   // |system_service| is NULL if Drive is disabled.
-  if (!system_service || !system_service->file_system())
+  if (!cache)
     return;
-  drive::DriveCache* cache = system_service->cache();
 
   // We check permissions for raw cache file paths only for read-only
   // operations (when fileEntry.file() is called), so read only permissions
   // should be sufficient for all cache paths. For the rest of supported
   // operations the file access check is done for drive/ paths.
   GrantFilePermissionsToHost(render_view_host,
                              cache->GetCacheDirectoryPath(
                                  drive::DriveCache::CACHE_TYPE_TMP),
                              file_handler_util::GetReadOnlyPermissions());
   GrantFilePermissionsToHost(
@@ skipping 3078 matching lines @@
 OpenNewWindowFunction::OpenNewWindowFunction() {}
 
 OpenNewWindowFunction::~OpenNewWindowFunction() {}
 
 bool OpenNewWindowFunction::RunImpl() {
   std::string url;
   EXTENSION_FUNCTION_VALIDATE(args_->GetString(0, &url));
   file_manager_util::OpenNewWindow(profile_, GURL(url));
   return true;
 }