Revert of Turn VariationsService::GetVariationsServerURL into instance method

chrome/browser/metrics/variations/variations_service.h

Index: chrome/browser/metrics/variations/variations_service.h
diff --git a/chrome/browser/metrics/variations/variations_service.h b/chrome/browser/metrics/variations/variations_service.h
index c0540d24bff87183fb72cb8fa168dc2e302f99f1..668f48d14e654634a88a79e747e7966f97ef72fb 100644
--- a/chrome/browser/metrics/variations/variations_service.h
+++ b/chrome/browser/metrics/variations/variations_service.h
@@ -109,8 +109,8 @@
   // Returns the variations server URL, which can vary if a command-line flag is
   // set and/or the variations restrict pref is set in |local_prefs|. Declared
   // static for test purposes.
-  GURL GetVariationsServerURL(PrefService* local_prefs,
-                              const std::string& restrict_mode_override);
+  static GURL GetVariationsServerURL(PrefService* local_prefs,
+                                     const std::string& restrict_mode_override);
 
   // Exposed for testing.
   static std::string GetDefaultVariationsServerURLForTesting();