Rearrange iOS SetupMetricsAndFieldTrials to SetupFieldTrials and SetupMetrics

ios/chrome/browser/ios_chrome_main_parts.h

Index: ios/chrome/browser/ios_chrome_main_parts.h
diff --git a/ios/chrome/browser/ios_chrome_main_parts.h b/ios/chrome/browser/ios_chrome_main_parts.h
index 8a372d9338bebb753c44493dc75bfbf46f6e73bc..74078862a59b8a93ec95a42271c10b39b6d8ed4f 100644
--- a/ios/chrome/browser/ios_chrome_main_parts.h
+++ b/ios/chrome/browser/ios_chrome_main_parts.h
@@ -36,10 +36,12 @@ class IOSChromeMainParts : public web::WebMainParts {
   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.