Rearrange iOS SetupMetricsAndFieldTrials to SetupFieldTrials and SetupMetrics

ios/chrome/browser/ios_chrome_main_parts.mm

 // Copyright 2016 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 "ios/chrome/browser/ios_chrome_main_parts.h"
 
 #include "base/base_switches.h"
 #include "base/feature_list.h"
 #include "base/files/file_path.h"
 #include "base/logging.h"
@@ skipping 96 matching lines @@
                          base::CommandLine::ForCurrentProcess());
 
   // Initialize tracking synchronizer system.
   tracking_synchronizer_ = new metrics::TrackingSynchronizer(
       base::MakeUnique<base::DefaultTickClock>(),
       base::Bind(&metrics::IOSTrackingSynchronizerDelegate::Create));
 
   // Now the command line has been mutated based on about:flags, we can setup
   // metrics and initialize field trials that are needed by IOSChromeIOThread's
   // initialization which happens in ApplicationContext:PreCreateThreads.
-  SetUpMetricsAndFieldTrials();
+  SetupFieldTrials();
+  SetupMetrics();
 
   // Initialize FieldTrialSynchronizer system.
   field_trial_synchronizer_.reset(new ios::FieldTrialSynchronizer);
 
   application_context_->PreCreateThreads();
 }
 
 void IOSChromeMainParts::PreMainMessageLoopRun() {
   // Now that the file thread has been started, start recording.
   StartMetricsRecording();
@@ skipping 57 matching lines @@
 void IOSChromeMainParts::PostMainMessageLoopRun() {
   TranslateServiceIOS::Shutdown();
   application_context_->StartTearDown();
 }
 
 void IOSChromeMainParts::PostDestroyThreads() {
   application_context_->PostDestroyThreads();
 }
 
 // This will be called after the command-line has been mutated by about:flags
-void IOSChromeMainParts::SetUpMetricsAndFieldTrials() {
+void IOSChromeMainParts::SetupFieldTrials() {
   base::SetRecordActionTaskRunner(
       web::WebThread::GetTaskRunnerForThread(web::WebThread::UI));
 
   // Initialize FieldTrialList to support FieldTrials that use one-time
   // randomization.
   DCHECK(!field_trial_list_);
   field_trial_list_.reset(
       new base::FieldTrialList(application_context_->GetMetricsServicesManager()
                                    ->CreateEntropyProvider()));
 
@@ skipping 12 matching lines @@
   }
 
   std::unique_ptr<base::FeatureList> feature_list(new base::FeatureList);
 
   // Associate parameters chosen in about:flags and create trial/group for them.
   flags_ui::PrefServiceFlagsStorage flags_storage(
       application_context_->GetLocalState());
   std::vector<std::string> variation_ids =
       RegisterAllFeatureVariationParameters(&flags_storage, feature_list.get());
 
-  // Must initialize metrics after about:flags have been converted into
-  // switches, but before field trials are set up (so that client ID is
-  // available for one-time randomized field trials).
-  metrics::MetricsService* metrics = application_context_->GetMetricsService();
-
   variations::VariationsHttpHeaderProvider* http_header_provider =
       variations::VariationsHttpHeaderProvider::GetInstance();
   // Force the variation ids selected in chrome://flags and/or specified using
   // the command-line flag.
   bool result = http_header_provider->ForceVariationIds(
       command_line->GetSwitchValueASCII(switches::kIOSForceVariationIds),
       &variation_ids);
   CHECK(result) << "Invalid list of variation ids specified (either in --"
                 << switches::kIOSForceVariationIds << " or in chrome://flags)";
-  metrics->AddSyntheticTrialObserver(http_header_provider);
 
   feature_list->InitializeFromCommandLine(
       command_line->GetSwitchValueASCII(switches::kEnableIOSFeatures),
       command_line->GetSwitchValueASCII(switches::kDisableIOSFeatures));
 
   variations::VariationsService* variations_service =
       application_context_->GetVariationsService();
   if (variations_service)
     variations_service->CreateTrialsFromSeed(feature_list.get());
 
   base::FeatureList::SetInstance(std::move(feature_list));
 
-  SetupFieldTrials(parsed_command_line_,
-                   base::Time::FromTimeT(metrics->GetInstallDate()));
+  SetupIOSFieldTrials();
+}
 
+void IOSChromeMainParts::SetupMetrics() {
+  metrics::MetricsService* metrics = application_context_->GetMetricsService();
+  metrics->AddSyntheticTrialObserver(
+      variations::VariationsHttpHeaderProvider::GetInstance());
   // Now that field trials have been created, initializes metrics recording.
   metrics->InitializeMetricsRecordingState();
 }
 
 void IOSChromeMainParts::StartMetricsRecording() {
   bool wifiOnly = local_state_->GetBoolean(prefs::kMetricsReportingWifiOnly);
   bool isConnectionCellular = net::NetworkChangeNotifier::IsConnectionCellular(
       net::NetworkChangeNotifier::GetConnectionType());
   bool mayUpload = !wifiOnly || !isConnectionCellular;
 
   application_context_->GetMetricsServicesManager()->UpdateUploadPermissions(
       mayUpload);
 }