[Sync] Renaming client key to client tag.

sync/internal_api/public/data_batch_impl.h

 // Copyright 2015 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 SYNC_INTERNAL_API_PUBLIC_DATA_BATCH_IMPL_H_
 #define SYNC_INTERNAL_API_PUBLIC_DATA_BATCH_IMPL_H_
 
 #include <stddef.h>
 
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "sync/api/data_batch.h"
 #include "sync/api/entity_data.h"
 
 namespace syncer_v2 {
 
 // An implementation of DataBatch that's purpose is to transfer ownership of
 // EntityData objects. As soon as this batch recieves the EntityData, it owns
 // them until Next() is invoked, when it gives up ownerhsip. Because a vector
-// is used internally, this impl is unaware when duplcate client_keys are used,
+// is used internally, this impl is unaware when duplcate client_tags are used,
 // and it is the caller's job to avoid this.
 class SYNC_EXPORT DataBatchImpl : public DataBatch {
  public:
   DataBatchImpl();
   ~DataBatchImpl() override;
 
-  // Takes ownership of the data tied to a given key used for storage. Put
-  // should be called at most once for any given client_key. Data will be
+  // Takes ownership of the data tied to a given tag used for storage. Put
+  // should be called at most once for any given client_tag. Data will be
   // readable in the same order that they are put into the batch.
-  void Put(const std::string& client_key, scoped_ptr<EntityData> entity_data);
+  void Put(const std::string& client_tag, scoped_ptr<EntityData> entity_data);
 
   // DataBatch implementation.
   bool HasNext() const override;
-  KeyAndData Next() override;
+  TagAndData Next() override;
 
  private:
-  std::vector<KeyAndData> key_data_pairs_;
+  std::vector<TagAndData> tag_data_pairs_;
   size_t read_index_ = 0;
 
   DISALLOW_COPY_AND_ASSIGN(DataBatchImpl);
 };
 
 }  // namespace syncer_v2
 
 #endif  // SYNC_INTERNAL_API_PUBLIC_DATA_BATCH_IMPL_H_