Remove root resource id aliasing from DriveResourceMetadata.

chrome/browser/chromeos/drive/stale_cache_files_remover_unittest.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 <string>
 #include <vector>
 
 #include "base/bind.h"
 #include "base/file_util.h"
 #include "base/files/file_path.h"
@@ skipping 63 matching lines @@
         pool->GetSequencedTaskRunner(pool->GetSequenceToken());
 
     // Likewise, this will be owned by DriveFileSystem.
     cache_.reset(new DriveCache(DriveCache::GetCacheRootPath(profile_.get()),
                                 blocking_task_runner_,
                                 fake_free_disk_space_getter_.get()));
 
     drive_webapps_registry_.reset(new DriveWebAppsRegistry);
 
     resource_metadata_.reset(new DriveResourceMetadata(
-        fake_drive_service_->GetRootResourceId(),
         cache_->GetCacheDirectoryPath(DriveCache::CACHE_TYPE_META),
         blocking_task_runner_));
 
     ASSERT_FALSE(file_system_);
     file_system_ = new DriveFileSystem(profile_.get(),
                                        cache_.get(),
                                        fake_drive_service_.get(),
                                        drive_webapps_registry_.get(),
                                        resource_metadata_.get(),
                                        blocking_task_runner_);
@@ skipping 91 matching lines @@
 
   // Verify that the cache entry is deleted.
   cache_->GetCacheEntry(resource_id, md5,
                         google_apis::test_util::CreateCopyResultCallback(
                             &success, &cache_entry));
   google_apis::test_util::RunBlockingPoolTask();
   EXPECT_FALSE(success);
 }
 
 }   // namespace drive