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

chrome/browser/chromeos/drive/file_system/operation_test_base.cc

Index: chrome/browser/chromeos/drive/file_system/operation_test_base.cc
diff --git a/chrome/browser/chromeos/drive/file_system/operation_test_base.cc b/chrome/browser/chromeos/drive/file_system/operation_test_base.cc
index d62f9148dd7d7a2ec2a126f760db590c19b7ae73..91879c2d3ac712b60f0f96459541bf80a0bc9763 100644
--- a/chrome/browser/chromeos/drive/file_system/operation_test_base.cc
+++ b/chrome/browser/chromeos/drive/file_system/operation_test_base.cc
@@ -111,17 +111,6 @@ void OperationTestBase::SetUp() {
   ASSERT_EQ(FILE_ERROR_OK, error);
 }
 
-void OperationTestBase::TearDown() {
-  cache_.reset();
-  fake_free_disk_space_getter_.reset();
-  metadata_.reset();
-  scheduler_.reset();
-  fake_drive_service_.reset();
-  profile_.reset();
-
-  blocking_task_runner_ = NULL;
-}
-
 FileError OperationTestBase::GetLocalResourceEntry(const base::FilePath& path,
                                                    ResourceEntry* entry) {
   FileError error = FILE_ERROR_FAILED;