Use low entropy for studies that send experiment IDs to Google properties.

components/variations/service/variations_service_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 "components/variations/service/variations_service.h"
 
 #include <stddef.h>
 
 #include <memory>
 #include <utility>
@@ skipping 115 matching lines @@
                  bool is_delta_compressed,
                  bool is_gzip_compressed) override {
     seed_stored_ = true;
     stored_seed_data_ = seed_data;
     stored_country_ = country_code;
     delta_compressed_seed_ = is_delta_compressed;
     gzip_compressed_seed_ = is_gzip_compressed;
     return true;
   }
 
+  std::unique_ptr<const base::FieldTrial::EntropyProvider>
+  CreateLowEntropyProvider() override {
+    return std::unique_ptr<const base::FieldTrial::EntropyProvider>(nullptr);
+  }
+
  private:
   bool LoadSeed(VariationsSeed* seed) override {
     if (!seed_stored_)
       return false;
     return seed->ParseFromString(stored_seed_data_);
   }
 
   bool intercepts_fetch_;
   bool fetch_attempted_;
   bool seed_stored_;
@@ skipping 137 matching lines @@
 
   // Store a seed.
   service.StoreSeed(SerializeSeed(CreateTestSeed()), std::string(),
                     std::string(), base::Time::Now(), false, false);
   prefs.SetInt64(prefs::kVariationsLastFetchTime,
                  base::Time::Now().ToInternalValue());
 
   // Check that field trials are created from the seed. Since the test study has
   // only 1 experiment with 100% probability weight, we must be part of it.
   EXPECT_TRUE(service.CreateTrialsFromSeed(base::FeatureList::GetInstance()));
-  EXPECT_EQ(base::FieldTrialList::FindFullName(kTestSeedStudyName),
-            kTestSeedExperimentName);
+  EXPECT_EQ(kTestSeedExperimentName,
+            base::FieldTrialList::FindFullName(kTestSeedStudyName));
 }
 
 TEST_F(VariationsServiceTest, CreateTrialsFromSeedNoLastFetchTime) {
   TestingPrefServiceSimple prefs;
   VariationsService::RegisterPrefs(prefs.registry());
 
   // Setup base::FeatureList.
   base::FeatureList::ClearInstanceForTesting();
   base::FeatureList::SetInstance(base::WrapUnique(new base::FeatureList()));
 
@@ skipping 480 matching lines @@
     }
     const base::ListValue* pref_value =
         prefs.GetList(prefs::kVariationsPermanentConsistencyCountry);
     EXPECT_EQ(ListValueToString(expected_list_value),
               ListValueToString(*pref_value))
         << test.pref_value_before << ", " << test.country_code_override;
   }
 }
 
 }  // namespace variations