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

components/variations/entropy_provider_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/entropy_provider.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <cmath>
@@ skipping 233 matching lines @@
 TEST(EntropyProviderTest, UseOneTimeRandomizationWithCustomSeedPermuted) {
   // Ensures that two trials with different names but the same custom seed used
   // for one time randomization produce the same group assignments.
   base::FieldTrialList field_trial_list(
       new PermutedEntropyProvider(1234, kMaxLowEntropySize));
   const int kNoExpirationYear = base::FieldTrialList::kNoExpirationYear;
   const uint32_t kCustomSeed = 9001;
   scoped_refptr<base::FieldTrial> trials[] = {
       base::FieldTrialList::FactoryGetFieldTrialWithRandomizationSeed(
           "one", 100, "default", kNoExpirationYear, 1, 1,
-          base::FieldTrial::ONE_TIME_RANDOMIZED, kCustomSeed, NULL),
+          base::FieldTrial::ONE_TIME_RANDOMIZED, kCustomSeed, NULL, NULL),
       base::FieldTrialList::FactoryGetFieldTrialWithRandomizationSeed(
           "two", 100, "default", kNoExpirationYear, 1, 1,
-          base::FieldTrial::ONE_TIME_RANDOMIZED, kCustomSeed, NULL),
+          base::FieldTrial::ONE_TIME_RANDOMIZED, kCustomSeed, NULL, NULL),
   };
 
   for (size_t i = 0; i < arraysize(trials); ++i) {
     for (int j = 0; j < 100; ++j)
       trials[i]->AppendGroup(std::string(), 1);
   }
 
   // Normally, these trials should produce different groups, but if the same
   // custom seed is used, they should produce the same group assignment.
   EXPECT_EQ(trials[0]->group(), trials[1]->group());
@@ skipping 93 matching lines @@
       ++count;
     }
 
     ASSERT_LT(count, kMaxAttempts) << "Expected average was " <<
         kExpectedAverage << ", average ended at " << cumulative_average <<
         ", for trial " << kTestTrialNames[i];
   }
 }
 
 }  // namespace metrics