[Sync] Replace typedef with using.

components/sync/engine_impl/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 "components/sync/engine_impl/attachments/attachment_downloader_impl.h"
 
 #include <map>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 126 matching lines @@
 
 OAuth2TokenService* TokenServiceProvider::GetTokenService() {
   DCHECK(task_runner_->BelongsToCurrentThread());
   return token_service_;
 }
 
 }  // namespace
 
 class AttachmentDownloaderImplTest : public testing::Test {
  protected:
-  typedef std::map<AttachmentId, AttachmentDownloader::DownloadResult>
-      ResultsMap;
+  using ResultsMap =
+      std::map<AttachmentId, AttachmentDownloader::DownloadResult>;
 
   enum HashHeaderType {
     HASH_HEADER_NONE,
     HASH_HEADER_VALID,
     HASH_HEADER_INVALID
   };
 
   AttachmentDownloaderImplTest()
       : num_completed_downloads_(0),
         attachment_id_(Attachment::Create(new base::RefCountedStaticMemory(
@@ skipping 368 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