[Sync] Add location parameter to SyncChange in Sync API.

sync/api/sync_change.h

 // Copyright (c) 2012 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_API_SYNC_CHANGE_H_
 #define SYNC_API_SYNC_CHANGE_H_
 #pragma once
 
 #include <iosfwd>
 #include <string>
 #include <vector>
 
+#include "base/location.h"
 #include "sync/api/sync_data.h"
 
 namespace syncer {
 
 // A SyncChange object reflects a change to a piece of synced data. The change
 // can be either a delete, add, or an update. All data relevant to the change
 // is encapsulated within the SyncChange, which, once created, is immutable.
 // Note: it is safe and cheap to pass these by value or make copies, as they do
 // not create deep copies of their internal data.
 class SyncChange {
  public:
   enum SyncChangeType {
     ACTION_INVALID,
     ACTION_ADD,
     ACTION_UPDATE,
     ACTION_DELETE
   };
 
   // Default constructor creates an invalid change.
   SyncChange();
   // Create a new change with the specified sync data.
-  SyncChange(SyncChangeType change_type, const SyncData& sync_data);
+  SyncChange(
+      const tracked_objects::Location& from_here,
+      SyncChangeType change_type,
+      const SyncData& sync_data);
   ~SyncChange();
 
   // Copy constructor and assignment operator welcome.
 
   // Whether this change is valid. This must be true before attempting to access
   // the data.
   // Deletes: Requires valid tag when going to the syncer. Requires valid
   //          specifics when coming from the syncer.
   // Adds, Updates: Require valid tag and specifics when going to the syncer.
   //                Require only valid specifics when coming from the syncer.
   bool IsValid() const;
 
   // Getters.
   SyncChangeType change_type() const;
   SyncData sync_data() const;
 
   // Returns a string representation of |change_type|.
   static std::string ChangeTypeToString(SyncChangeType change_type);
 
   // Returns a string representation of the entire object. Used for gmock
   // printing method, PrintTo.
   std::string ToString() const;
 
  private:
+  tracked_objects::Location location_;
+
   SyncChangeType change_type_;
 
   // An immutable container for the data of this SyncChange. Whenever
   // SyncChanges are copied, they copy references to this data.
   SyncData sync_data_;
 };
 
 // gmock printer helper.
 void PrintTo(const SyncChange& sync_change, std::ostream* os);
 
 }  // namespace syncer
 
 #endif  // SYNC_API_SYNC_CHANGE_H_