Use a different algorithm with the low entropy source for field trials.

chrome/common/metrics/variations/variations_util_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.
 
 // Tests for the Variations Helpers.
 
 #include <set>
 
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop.h"
@@ skipping 12 matching lines @@
 // FieldTrial. Note that this will do the group assignment in |trial| if not
 // already done.
 chrome_variations::VariationID GetIDForTrial(base::FieldTrial* trial) {
   return GetGoogleVariationID(trial->name(), trial->group_name());
 }
 
 }  // namespace
 
 class VariationsHelperTest : public ::testing::Test {
  public:
-  VariationsHelperTest() {
+  VariationsHelperTest() : field_trial_list_(NULL) {
     // Since the API can only be called on the UI thread, we have to fake that
     // we're on it.
     ui_thread_.reset(new content::TestBrowserThread(
         content::BrowserThread::UI, &message_loop_));
 
     base::Time now = base::Time::NowFromSystemTime();
     base::TimeDelta oneYear = base::TimeDelta::FromDays(365);
     base::Time::Exploded exploded;
 
     base::Time next_year_time = now + oneYear;
     next_year_time.LocalExplode(&exploded);
     next_year_ = exploded.year;
   }
 
  protected:
   int next_year_;
 
  private:
+  base::FieldTrialList field_trial_list_;
   MessageLoop message_loop_;
   scoped_ptr<content::TestBrowserThread> ui_thread_;
 };
 
 TEST_F(VariationsHelperTest, HashName) {
   // Make sure hashing is stable on all platforms.
   struct {
     const char* name;
     uint32 hash_value;
   } known_hashes[] = {
@@ skipping 205 matching lines @@
 
     std::vector<string16> chunks;
     GenerateVariationChunks(experiments, &chunks);
     ASSERT_EQ(cases[i].expected_chunks_length, chunks.size());
     for (size_t j = 0; j < chunks.size(); ++j)
       EXPECT_EQ(UTF8ToUTF16(cases[i].expected_chunks[j]), chunks[j]);
   }
 }
 
 }  // namespace chrome_variations