Convert JsonWriter::Write to taking a const ref for the in-param

extensions/common/permissions/set_disjunction_permission.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 EXTENSIONS_COMMON_PERMISSIONS_SET_DISJUNCTION_PERMISSION_H_
 #define EXTENSIONS_COMMON_PERMISSIONS_SET_DISJUNCTION_PERMISSION_H_
 
 #include <set>
 #include <string>
 
@@ skipping 104 matching lines @@
       const base::Value* item_value = NULL;
       bool got_item = list->Get(i, &item_value);
       DCHECK(got_item);
       DCHECK(item_value);
 
       PermissionDataType data;
       if (data.FromValue(item_value)) {
         data_set_.insert(data);
       } else {
         std::string unknown_permission;
-        base::JSONWriter::Write(item_value, &unknown_permission);
+        base::JSONWriter::Write(*item_value, &unknown_permission);
         if (unhandled_permissions) {
           unhandled_permissions->push_back(unknown_permission);
         } else {
           if (error) {
             *error = "Cannot parse an item from the permission list: " +
                      unknown_permission;
           }
           return false;
         }
       }
@@ skipping 23 matching lines @@
     IPC::LogParam(data_set_, log);
   }
 
  protected:
   std::set<PermissionDataType> data_set_;
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_COMMON_PERMISSIONS_SET_DISJUNCTION_PERMISSION_H_