Store field trial parameters in shared memory

base/metrics/field_trial_unittest.cc

 // 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.
 
 #include "base/metrics/field_trial.h"
 
 #include <stddef.h>
 
 #include "base/base_switches.h"
 #include "base/build_time.h"
 #include "base/feature_list.h"
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/message_loop/message_loop.h"
+#include "base/metrics/field_trial_param_associator.h"
 #include "base/rand_util.h"
 #include "base/run_loop.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/stringprintf.h"
 #include "base/test/gtest_util.h"
 #include "base/test/mock_entropy_provider.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace base {
 
@@ skipping 1162 matching lines @@
 
   FieldTrialList field_trial_list2(nullptr);
   std::unique_ptr<base::SharedMemory> shm(new SharedMemory(handle, true));
   shm.get()->Map(4 << 10);  // Hardcoded, equal to kFieldTrialAllocationSize.
   FieldTrialList::CreateTrialsFromSharedMemory(std::move(shm));
   std::string check_string;
   FieldTrialList::AllStatesToString(&check_string);
   EXPECT_EQ(save_string, check_string);
 }
 
+TEST(FieldTrialListTest, AssociateFieldTrialParams) {
+  std::string trial_name("Trial1");
+  std::string group_name("Group1");
+
+  // Create a field trial with some params.
+  FieldTrialList field_trial_list(nullptr);
+  FieldTrialList::CreateFieldTrial(trial_name, group_name);
+  std::map<std::string, std::string> params;
+  params["key1"] = "value1";
+  params["key2"] = "value2";
+  FieldTrialParamAssociator::GetInstance()->AssociateFieldTrialParams(
+      trial_name, group_name, params);
+  FieldTrialList::InstantiateFieldTrialAllocatorIfNeeded();
+
+  // Clear all cached params from the associator.
+  FieldTrialParamAssociator::GetInstance()->ClearAllCachedParamsForTesting();
+
+  // Check that we fetch the param from shared memory properly.
+  std::map<std::string, std::string> new_params;
+  FieldTrialParamAssociator::GetInstance()->GetFieldTrialParams(trial_name,
+                                                                &new_params);
+  EXPECT_EQ("value1", new_params["key1"]);
+  EXPECT_EQ("value2", new_params["key2"]);
+  EXPECT_EQ(static_cast<unsigned long>(2), new_params.size());

[Alexei Svitkine (slow), 2016/11/23 17:23:40]

Instead of the cast, I think you can do 2U

[lawrencewu, 2016/11/23 19:07:33]

Done.

+}
+
 }  // namespace base