Support add-on 'field trial' records.

components/variations/active_field_trials.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/variations/active_field_trials.h"
 
 #include <stddef.h>
 
 #include <vector>
 
@@ skipping 22 matching lines @@
     const std::vector<ActiveGroupId> name_group_ids,
     std::vector<std::string>* output) {
   for (const auto& active_group_id : name_group_ids) {
     output->push_back(base::StringPrintf("%x-%x", active_group_id.name,
                                          active_group_id.group));
   }
 }
 
 }  // namespace
 
-ActiveGroupId MakeActiveGroupId(const std::string& trial_name,
-                                const std::string& group_name) {
+ActiveGroupId MakeActiveGroupId(base::StringPiece trial_name,
+                                base::StringPiece group_name) {
   ActiveGroupId id;
   id.name = metrics::HashName(trial_name);
   id.group = metrics::HashName(group_name);
   return id;
 }
 
 void GetFieldTrialActiveGroupIds(
     std::vector<ActiveGroupId>* name_group_ids) {
   DCHECK(name_group_ids->empty());
   // A note on thread safety: Since GetActiveFieldTrialGroups() is thread
@@ skipping 24 matching lines @@
 void TestGetFieldTrialActiveGroupIds(
     const base::FieldTrial::ActiveGroups& active_groups,
     std::vector<ActiveGroupId>* name_group_ids) {
   GetFieldTrialActiveGroupIdsForActiveGroups(active_groups,
                                              name_group_ids);
 }
 
 }  // namespace testing
 
 }  // namespace variations