Revert of Supporting study definitions without default groups and end_date filtering.

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 d2b5130878efd65d0e0b1b7d8d067ef218bef795..7703eed3b1ae1631c2f014239fc2d77dd575b1d3 100644
--- a/components/variations/variations_seed_processor_unittest.cc
+++ b/components/variations/variations_seed_processor_unittest.cc
@@ -378,9 +378,8 @@
   study.mutable_filter()->set_max_version("2.3.4");
   EXPECT_TRUE(processed_study.Init(&study, false));
 
-  // A blank default study is allowed.
   study.clear_default_experiment_name();
-  EXPECT_TRUE(processed_study.Init(&study, false));
+  EXPECT_FALSE(processed_study.Init(&study, false));
 
   study.set_default_experiment_name("xyz");
   EXPECT_FALSE(processed_study.Init(&study, false));
@@ -846,23 +845,6 @@
   }
 }
 
-TEST_F(VariationsSeedProcessorTest, NoDefaultExperiment) {
-  base::FieldTrialList field_trial_list(nullptr);
-
-  Study study;
-  study.set_name("Study1");
-
-  AddExperiment("A", 1, &study);
-
-  EXPECT_TRUE(CreateTrialFromStudy(study));
-
-  base::FieldTrial* trial = base::FieldTrialList::Find("Study1");
-  trial->Disable();
-
-  EXPECT_EQ(ProcessedStudy::kGenericDefaultExperimentName,
-            base::FieldTrialList::FindFullName("Study1"));
-}
-
 TEST_F(VariationsSeedProcessorTest, LowEntropyStudyTest) {
   const std::string kTrial1Name = "A";
   const std::string kTrial2Name = "B";