Move more metrics classes to metrics namespace.

components/metrics/metrics_service.cc

Index: components/metrics/metrics_service.cc
diff --git a/components/metrics/metrics_service.cc b/components/metrics/metrics_service.cc
index 3c499c14e671415bfd2414e05389a73f4720fd9d..ca9fef4fea954d01245ca6370557befef2464fa7 100644
--- a/components/metrics/metrics_service.cc
+++ b/components/metrics/metrics_service.cc
@@ -191,8 +191,7 @@
 #include "components/metrics/metrics_state_manager.h"
 #include "components/variations/entropy_provider.h"
 
-using base::Time;
-using metrics::MetricsLogManager;
+namespace metrics {
 
 namespace {
 
@@ -613,7 +612,7 @@ void MetricsService::InitializeMetricsState() {
   // them.  metrics::prefs::kStabilityLastTimestampSec may also be useless now.
   // TODO(jar): Delete these if they have no uses.
   local_state_->SetInt64(metrics::prefs::kStabilityLaunchTimeSec,
-                         Time::Now().ToTimeT());
+                         base::Time::Now().ToTimeT());
 
   // Bookkeeping for the uninstall metrics.
   IncrementLongPrefsValue(metrics::prefs::kUninstallLaunchCount);
@@ -1190,5 +1189,7 @@ void MetricsService::RecordBooleanPrefValue(const char* path, bool value) {
 
 void MetricsService::RecordCurrentState(PrefService* pref) {
   pref->SetInt64(metrics::prefs::kStabilityLastTimestampSec,
-                 Time::Now().ToTimeT());
+                 base::Time::Now().ToTimeT());
 }
+
+}  // namespace metrics