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

components/variations/variations_seed_processor_unittest.cc

Index: components/variations/variations_seed_processor_unittest.cc
diff --git a/components/variations/variations_seed_processor_unittest.cc b/components/variations/variations_seed_processor_unittest.cc
index d6207ff328868fb28d8afb432dbe794e5f32e744..1ab8a497a38411046a4c3090e804444be1d9606b 100644
--- a/components/variations/variations_seed_processor_unittest.cc
+++ b/components/variations/variations_seed_processor_unittest.cc
@@ -40,6 +40,7 @@ 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";
 
@@ -227,6 +228,20 @@ TEST_F(VariationsSeedProcessorTest, ForceGroup_DontChooseGroupWithFlag) {
             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;