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

components/metrics/metrics_service.cc

 // Copyright 2014 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.
 
 //------------------------------------------------------------------------------
 // Description of the life cycle of a instance of MetricsService.
 //
 //  OVERVIEW
 //
 // A MetricsService instance is typically created at application startup.  It is
@@ skipping 365 matching lines @@
 }
 
 bool MetricsService::WasLastShutdownClean() const {
   return clean_exit_beacon_.exited_cleanly();
 }
 
 std::unique_ptr<const base::FieldTrial::EntropyProvider>
 MetricsService::CreateEntropyProvider() {
   // TODO(asvitkine): Refactor the code so that MetricsService does not expose
   // this method.
-  return state_manager_->CreateEntropyProvider();
+  return state_manager_->CreateDefaultEntropyProvider();
 }
 
 void MetricsService::EnableRecording() {
   DCHECK(IsSingleThreaded());
 
   if (recording_state_ == ACTIVE)
     return;
   recording_state_ = ACTIVE;
 
   state_manager_->ForceClientIdCreation();
@@ skipping 796 matching lines @@
                  base::Time::Now().ToTimeT());
 }
 
 void MetricsService::SkipAndDiscardUpload() {
   log_manager_.DiscardStagedLog();
   scheduler_->UploadCancelled();
   log_upload_in_progress_ = false;
 }
 
 }  // namespace metrics