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

chrome/browser/chromeos/drive/drive_file_stream_reader_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/drive_file_stream_reader.h"
 
 #include <string>
 
 #include "base/bind.h"
 #include "base/files/file_path.h"
@@ skipping 33 matching lines @@
 
   virtual void SetUp() OVERRIDE {
     ASSERT_TRUE(temp_dir_.CreateUniqueTempDir());
     ASSERT_TRUE(google_apis::test_util::CreateFileOfSpecifiedSize(
         temp_dir_.path(), 1024, &file_path_, &file_content_));
 
     worker_thread_.reset(new base::Thread("ReaderProxyTest"));
     ASSERT_TRUE(worker_thread_->Start());
   }
 
-  virtual void TearDown() OVERRIDE {
-    worker_thread_.reset();
-  }
-
   content::TestBrowserThreadBundle thread_bundle_;
 
   base::ScopedTempDir temp_dir_;
   base::FilePath file_path_;
   std::string file_content_;
 
   scoped_ptr<base::Thread> worker_thread_;
 };
 
 TEST_F(LocalReaderProxyTest, Read) {
@@ skipping 425 matching lines @@
         google_apis::test_util::CreateQuitCallback(
             &run_loop,
             google_apis::test_util::CreateCopyResultCallback(&error, &entry)));
     run_loop.Run();
   }
   EXPECT_EQ(net::ERR_REQUEST_RANGE_NOT_SATISFIABLE, error);
   EXPECT_FALSE(entry);
 }
 
 }  // namespace drive