Fix crash when variation parameters are set in chrome://flags.

components/variations/variations_seed_processor_unittest.cc

 // Copyright 2013 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/variations_seed_processor.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <map>
@@ skipping 22 matching lines @@
 // Converts |time| to Study proto format.
 int64_t TimeToProtoTime(const base::Time& time) {
   return (time - base::Time::UnixEpoch()).InSeconds();
 }
 
 // Constants for testing associating command line flags with trial groups.
 const char kFlagStudyName[] = "flag_test_trial";
 const char kFlagGroup1Name[] = "flag_group1";
 const char kFlagGroup2Name[] = "flag_group2";
 const char kNonFlagGroupName[] = "non_flag_group";
+const char kOtherGroupName[] = "other_group";
 const char kForcingFlag1[] = "flag_test1";
 const char kForcingFlag2[] = "flag_test2";
 
 const VariationID kExperimentId = 123;
 
 // Adds an experiment to |study| with the specified |name| and |probability|.
 Study_Experiment* AddExperiment(const std::string& name, int probability,
                                 Study* study) {
   Study_Experiment* experiment = study->add_experiment();
   experiment->set_name(name);
@@ skipping 167 matching lines @@
 
   // The two flag groups are given high probability, which would normally make
   // them very likely to be chosen. They won't be chosen since flag groups are
   // never chosen when their flag isn't present.
   Study study = CreateStudyWithFlagGroups(1, 999, 999);
   EXPECT_TRUE(CreateTrialFromStudy(study));
   EXPECT_EQ(kNonFlagGroupName,
             base::FieldTrialList::FindFullName(kFlagStudyName));
 }
 
+TEST_F(VariationsSeedProcessorTest, CreateTrialForRegisteredGroup) {
+  base::FieldTrialList field_trial_list(nullptr);
+
+  base::FieldTrialList::CreateFieldTrial(kFlagStudyName, kOtherGroupName);
+
+  // Create an arbitrary study that does not have group named |kOtherGroupName|.
+  Study study = CreateStudyWithFlagGroups(100, 0, 0);
+  // Creating the trial should not crash.
+  EXPECT_TRUE(CreateTrialFromStudy(study));
+  // And the previous group should still be selected.
+  EXPECT_EQ(kOtherGroupName,
+            base::FieldTrialList::FindFullName(kFlagStudyName));
+}
+
 TEST_F(VariationsSeedProcessorTest,
        NonExpiredStudyPrioritizedOverExpiredStudy) {
   VariationsSeedProcessor seed_processor;
 
   const std::string kTrialName = "A";
   const std::string kGroup1Name = "Group1";
 
   VariationsSeed seed;
   Study* study1 = seed.add_study();
   study1->set_name(kTrialName);
@@ skipping 632 matching lines @@
   // Since no experiment in study1 sends experiment IDs, it will use the high
   // entropy provider, which selects the non-default group.
   EXPECT_EQ(kGroup1Name, base::FieldTrialList::FindFullName(kTrial1Name));
 
   // Since an experiment in study2 has google_web_experiment_id set, it will use
   // the low entropy provider, which selects the default group.
   EXPECT_EQ(kDefaultName, base::FieldTrialList::FindFullName(kTrial2Name));
 }
 
 }  // namespace variations