[Sync] Replace typedef with using.

components/sync/model/attachments/attachment_store.h

 // 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.
 
 #ifndef COMPONENTS_SYNC_MODEL_ATTACHMENTS_ATTACHMENT_STORE_H_
 #define COMPONENTS_SYNC_MODEL_ATTACHMENTS_ATTACHMENT_STORE_H_
 
 #include <memory>
 
 #include "base/callback.h"
@@ skipping 39 matching lines @@
       10;  // Size of the Result enum; used for histograms.
 
   // Each attachment can have references from sync or model type. Tracking these
   // references is needed for lifetime management of attachment, it can only be
   // deleted from the store when it doesn't have references.
   enum Component {
     MODEL_TYPE,
     SYNC,
   };
 
-  typedef base::Callback<void(const Result&)> InitCallback;
-  typedef base::Callback<void(const Result&,
-                              std::unique_ptr<AttachmentMap>,
-                              std::unique_ptr<AttachmentIdList>)>
-      ReadCallback;
-  typedef base::Callback<void(const Result&)> WriteCallback;
-  typedef base::Callback<void(const Result&)> DropCallback;
-  typedef base::Callback<void(const Result&,
-                              std::unique_ptr<AttachmentMetadataList>)>
-      ReadMetadataCallback;
+  using InitCallback = base::Callback<void(const Result&)>;
+  using ReadCallback = base::Callback<void(const Result&,
+                                           std::unique_ptr<AttachmentMap>,
+                                           std::unique_ptr<AttachmentIdList>)>;
+  using WriteCallback = base::Callback<void(const Result&)>;
+  using DropCallback = base::Callback<void(const Result&)>;
+  using ReadMetadataCallback =
+      base::Callback<void(const Result&,
+                          std::unique_ptr<AttachmentMetadataList>)>;
 
   ~AttachmentStore();
 
   // Asynchronously reads the attachments identified by |ids|.
   //
   // |callback| will be invoked when finished. AttachmentStore will attempt to
   // read all attachments specified in ids. If any of the attachments do not
   // exist or could not be read, |callback|'s Result will be UNSPECIFIED_ERROR.
   // Callback's AttachmentMap will contain all attachments that were
   // successfully read, AttachmentIdList will contain attachment ids of
@@ skipping 121 matching lines @@
   // |sync_component_| is passed to frontend when sync related operations are
   // perfromed.
   const Component sync_component_;
 
   DISALLOW_COPY_AND_ASSIGN(AttachmentStoreForSync);
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_MODEL_ATTACHMENTS_ATTACHMENT_STORE_H_