Remove destruction-only TearDown() methods in Drive related test.

chrome/browser/chromeos/drive/webkit_file_stream_reader_impl_unittest.cc

 // Copyright 2013 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/drive/webkit_file_stream_reader_impl.h"
 
 #include <string>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 34 matching lines @@
         "gdata/root_feed.json");
     fake_drive_service_->LoadAccountMetadataForWapi(
         "gdata/account_metadata.json");
 
     // Create a testee instance.
     fake_file_system_.reset(
         new test_util::FakeFileSystem(fake_drive_service_.get()));
     fake_file_system_->Initialize();
   }
 
-  virtual void TearDown() OVERRIDE {
-    fake_file_system_.reset();
-    fake_drive_service_.reset();
-
-    worker_thread_.reset();
-  }
-
   FileSystemInterface* GetFileSystem() {
     return fake_file_system_.get();
   }
 
   DriveFileStreamReader::FileSystemGetter GetFileSystemGetter() {
     return base::Bind(&WebkitFileStreamReaderImplTest::GetFileSystem,
                       base::Unretained(this));
   }
 
   content::TestBrowserThreadBundle thread_bundle_;
@@ skipping 143 matching lines @@
           base::Time::FromInternalValue(1)));
 
   net::TestInt64CompletionCallback callback;
   int64 result = reader->GetLength(callback.callback());
   result = callback.GetResult(result);
   EXPECT_EQ(net::ERR_UPLOAD_FILE_CHANGED, result);
 }
 
 }  // namespace internal
 }  // namespace drive