Re-land: "Use an explicit identifier in Config"

webrtc/test/common_unittest.cc

 /*
  *  Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 #include "webrtc/common.h"
 
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace webrtc {
 namespace {
 
 struct MyExperiment {
+  static const ConfigOptionID identifier = ConfigOptionID::kMyExperimentForTest;
   static const int kDefaultFactor;
   static const int kDefaultOffset;
 
   MyExperiment()
     : factor(kDefaultFactor), offset(kDefaultOffset) {}
 
   MyExperiment(int factor, int offset)
     : factor(factor), offset(offset) {}
 
   int factor;
@@ skipping 21 matching lines @@
 TEST(Config, SetNullSetsTheOptionBackToDefault) {
   Config config;
   config.Set<MyExperiment>(new MyExperiment(5, 1));
   config.Set<MyExperiment>(NULL);
   const MyExperiment& my_exp = config.Get<MyExperiment>();
   EXPECT_EQ(MyExperiment::kDefaultFactor, my_exp.factor);
   EXPECT_EQ(MyExperiment::kDefaultOffset, my_exp.offset);
 }
 
 struct Algo1_CostFunction {
+  static const ConfigOptionID identifier =
+      ConfigOptionID::kAlgo1CostFunctionForTest;
   Algo1_CostFunction() {}
 
   virtual int cost(int x) const {
     return x;
   }
 
   virtual ~Algo1_CostFunction() {}
 };
 
 struct SqrCost : Algo1_CostFunction {
   virtual int cost(int x) const {
     return x*x;
   }
 };
 
 TEST(Config, SupportsPolymorphism) {
   Config config;
   config.Set<Algo1_CostFunction>(new SqrCost());
   EXPECT_EQ(25, config.Get<Algo1_CostFunction>().cost(5));
 }
 }  // namespace
 }  // namespace webrtc