Remove MetricsServiceObserver in favor of MetricsProvider.

chrome/browser/metrics/metrics_service_accessor.cc

 // Copyright 2014 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 "chrome/browser/metrics/metrics_service_accessor.h"
 
-#include "chrome/browser/browser_process.h"
 #include "components/metrics/metrics_service.h"
-#include "components/metrics/metrics_service_observer.h"
 
 // TODO(asvitkine): Remove when this class is moved to metrics namespace.
 using metrics::MetricsService;
-using metrics::MetricsServiceObserver;
 using metrics::SyntheticTrialGroup;
 
 // static
-void MetricsServiceAccessor::AddMetricsServiceObserver(
-    MetricsServiceObserver* observer) {
-  MetricsService* metrics_service = g_browser_process->metrics_service();
-  if (metrics_service)
-    metrics_service->AddObserver(observer);
-}
-
-void MetricsServiceAccessor::RemoveMetricsServiceObserver(
-    MetricsServiceObserver* observer) {
-  MetricsService* metrics_service = g_browser_process->metrics_service();
-  if (metrics_service)
-    metrics_service->RemoveObserver(observer);
-}
-
-// static
 bool MetricsServiceAccessor::RegisterSyntheticFieldTrial(
     MetricsService* metrics_service,
     uint32_t trial_name_hash,
     uint32_t group_name_hash) {
   if (!metrics_service)
     return false;
 
   SyntheticTrialGroup trial_group(trial_name_hash, group_name_hash);
   metrics_service->RegisterSyntheticFieldTrial(trial_group);
   return true;
 }