Rearrange iOS SetupMetricsAndFieldTrials to SetupFieldTrials and SetupMetrics

ios/chrome/browser/ios_chrome_main_parts.h

 // 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.
 
 #ifndef IOS_CHROME_BROWSER_IOS_CHROME_MAIN_PARTS_H_
 #define IOS_CHROME_BROWSER_IOS_CHROME_MAIN_PARTS_H_
 
 #include <memory>
 
 #include "base/command_line.h"
@@ skipping 18 matching lines @@
   ~IOSChromeMainParts() override;
 
  private:
   // web::WebMainParts implementation.
   void PreMainMessageLoopStart() override;
   void PreCreateThreads() override;
   void PreMainMessageLoopRun() override;
   void PostMainMessageLoopRun() override;
   void PostDestroyThreads() override;
 
-  // Constructs metrics service and does related initialization, including
-  // creation of field trials. Call only after labs have been converted to
-  // switches.
-  void SetUpMetricsAndFieldTrials();
+  // Sets up the field trials and related initialization. Call only after
+  // about:flags have been converted to switches.
+  void SetupFieldTrials();
+
+  // Constructs the metrics service and initializes metrics recording.
+  void SetupMetrics();
 
   // Starts recording of metrics. This can only be called after we have a file
   // thread.
   void StartMetricsRecording();
 
   const base::CommandLine& parsed_command_line_;
 
   std::unique_ptr<ApplicationContextImpl> application_context_;
   scoped_refptr<metrics::TrackingSynchronizer> tracking_synchronizer_;
 
   // Statistical testing infrastructure for the entire browser. NULL until
   // SetUpMetricsAndFieldTrials is called.
   std::unique_ptr<base::FieldTrialList> field_trial_list_;
 
   PrefService* local_state_;
 
   // Initialized in SetupMetricsAndFieldTrials.
   std::unique_ptr<ios::FieldTrialSynchronizer> field_trial_synchronizer_;
 
   DISALLOW_COPY_AND_ASSIGN(IOSChromeMainParts);
 };
 
 #endif  // IOS_CHROME_BROWSER_IOS_CHROME_MAIN_PARTS_H_