Move more metrics classes to metrics namespace.

BUG=374763
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Review URL: https://codereview.chromium.org/502173002

Cr-Commit-Position: refs/heads/master@{#291994}
diff --git a/chrome/browser/metrics/chrome_metrics_service_client.h b/chrome/browser/metrics/chrome_metrics_service_client.h
index bc3c14a..e98b3133 100644
--- a/chrome/browser/metrics/chrome_metrics_service_client.h
+++ b/chrome/browser/metrics/chrome_metrics_service_client.h
@@ -21,7 +21,6 @@
 
 class ChromeOSMetricsProvider;
 class GoogleUpdateMetricsProviderWin;
-class MetricsService;
 class PluginMetricsProvider;
 class PrefRegistrySimple;
 class ProfilerMetricsProvider;
@@ -35,6 +34,7 @@
 }
 
 namespace metrics {
+class MetricsService;
 class MetricsStateManager;
 }
 
@@ -72,7 +72,7 @@
       const std::string& mime_type,
       const base::Callback<void(int)>& on_upload_complete) OVERRIDE;
 
-  MetricsService* metrics_service() { return metrics_service_.get(); }
+  metrics::MetricsService* metrics_service() { return metrics_service_.get(); }
 
   void LogPluginLoadingError(const base::FilePath& plugin_path);
 
@@ -131,7 +131,7 @@
   metrics::MetricsStateManager* metrics_state_manager_;
 
   // The MetricsService that |this| is a client of.
-  scoped_ptr<MetricsService> metrics_service_;
+  scoped_ptr<metrics::MetricsService> metrics_service_;
 
   content::NotificationRegistrar registrar_;