Select precache resources based on field trial experiment group

components/precache/content/precache_manager.cc

 // Copyright 2013 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/precache/content/precache_manager.h"
 
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/metrics/field_trial.h"
 #include "base/strings/string_util.h"
 #include "base/time/time.h"
 #include "components/history/core/browser/history_service.h"
 #include "components/precache/core/precache_database.h"
 #include "components/precache/core/precache_switches.h"
 #include "components/precache/core/proto/unfinished_work.pb.h"
 #include "components/prefs/pref_service.h"
 #include "components/sync_driver/sync_service.h"
+#include "components/variations/metrics_util.h"
 #include "components/variations/variations_associated_data.h"
 #include "content/public/browser/browser_context.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/storage_partition.h"
 #include "net/base/network_change_notifier.h"
 
 using content::BrowserThread;
 
 namespace {
 
@@ skipping 275 matching lines @@
 }
 
 void PrecacheManager::InitializeAndStartFetcher() {
   if (!is_precaching_) {
     // Don't start precaching if it was canceled while waiting for the list of
     // hosts.
     return;
   }
   // Start precaching.
   precache_fetcher_.reset(new PrecacheFetcher(
-      content::BrowserContext::GetDefaultStoragePartition(browser_context_)->
-            GetURLRequestContext(),
-      GURL(variations::GetVariationParamValue(
-          kPrecacheFieldTrialName, kConfigURLParam)),
-      variations::GetVariationParamValue(
-          kPrecacheFieldTrialName, kManifestURLPrefixParam),
+      content::BrowserContext::GetDefaultStoragePartition(browser_context_)
+          ->GetURLRequestContext(),
+      GURL(variations::GetVariationParamValue(kPrecacheFieldTrialName,
+                                              kConfigURLParam)),
+      variations::GetVariationParamValue(kPrecacheFieldTrialName,
+                                         kManifestURLPrefixParam),
       std::move(unfinished_work_),
+      metrics::HashName(
+          base::FieldTrialList::FindFullName(kPrecacheFieldTrialName)),
       this));
   precache_fetcher_->Start();
 }
 
 void PrecacheManager::OnHostsReceivedThenDone(
     const history::TopHostsList& host_counts) {
   OnDone();
 }
 
 }  // namespace precache