Store and retrieve features from shared memory

base/metrics/field_trial_unittest.cc

Index: base/metrics/field_trial_unittest.cc
diff --git a/base/metrics/field_trial_unittest.cc b/base/metrics/field_trial_unittest.cc
index 6c070268f1c2fb057d85c28c2418474d37de32dc..d2597f9eeb76ca5fc5d5d8eee6e6948261d27e26 100644
--- a/base/metrics/field_trial_unittest.cc
+++ b/base/metrics/field_trial_unittest.cc
@@ -1145,15 +1145,21 @@ TEST(FieldTrialListTest, TestCopyFieldTrialStateToFlags) {
   base::FilePath test_file_path = base::FilePath(FILE_PATH_LITERAL("Program"));
   base::CommandLine cmd_line = base::CommandLine(test_file_path);
   const char field_trial_handle[] = "test-field-trial-handle";
+  const char enable_features_switch[] = "test-enable-features";
+  const char disable_features_switch[] = "test-disable-features";
 
-  base::FieldTrialList::CopyFieldTrialStateToFlags(field_trial_handle,
-                                                   &cmd_line);
+  base::FieldTrialList::CopyFieldTrialStateToFlags(
+      field_trial_handle, enable_features_switch, disable_features_switch,
+      &cmd_line);
   EXPECT_TRUE(cmd_line.HasSwitch(field_trial_handle) ||
               cmd_line.HasSwitch(switches::kForceFieldTrials));
 }
 #endif
 
+#if !defined(OS_IOS)
 TEST(FieldTrialListTest, InstantiateAllocator) {
+  std::unique_ptr<FeatureList> feature_list(new FeatureList);

[Alexei Svitkine (slow), 2016/12/02 20:14:28]

This doesn't actually register the instance. (It doesn't work same way as
FieldTrialList.)

Can you use ScopedFeatureList here?

[lawrencewu, 2016/12/02 20:36:32]

Done. This also turned out to be the cause of those iossim crashes (the
singleton was null).

+
   FieldTrialList field_trial_list(nullptr);
   FieldTrialList::CreateFieldTrial("Trial1", "Group1");
 
@@ -1168,6 +1174,7 @@ TEST(FieldTrialListTest, InstantiateAllocator) {
   EXPECT_EQ(memory, new_memory);
   EXPECT_EQ(used, new_used);
 }
+#endif
 
 TEST(FieldTrialListTest, AddTrialsToAllocator) {
   std::string save_string;