Standardize usage of virtual/override/final specifiers in sync/.

sync/internal_api/attachments/attachment_downloader_impl_unittest.cc

 // Copyright 2014 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 "sync/internal_api/public/attachments/attachment_downloader_impl.h"
 
 #include "base/bind.h"
 #include "base/memory/weak_ptr.h"
 #include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
@@ skipping 136 matching lines @@
       ResultsMap;
 
   enum HashHeaderType {
     HASH_HEADER_NONE,
     HASH_HEADER_VALID,
     HASH_HEADER_INVALID
   };
 
   AttachmentDownloaderImplTest() : num_completed_downloads_(0) {}
 
-  virtual void SetUp() override;
-  virtual void TearDown() override;
+  void SetUp() override;
+  void TearDown() override;
 
   AttachmentDownloader* downloader() { return attachment_downloader_.get(); }
 
   MockOAuth2TokenService* token_service() { return token_service_.get(); }
 
   int num_completed_downloads() { return num_completed_downloads_; }
 
   AttachmentDownloader::DownloadCallback download_callback(
       const AttachmentId& id) {
     return base::Bind(&AttachmentDownloaderImplTest::DownloadDone,
@@ skipping 336 matching lines @@
   raw += "\n";
   std::replace(raw.begin(), raw.end(), '\n', '\0');
   scoped_refptr<net::HttpResponseHeaders> headers(
       new net::HttpResponseHeaders(raw));
   uint32_t extracted;
   ASSERT_FALSE(
       AttachmentDownloaderImpl::ExtractCrc32c(headers.get(), &extracted));
 }
 
 }  // namespace syncer