Move more metrics classes to metrics namespace.

components/metrics/metrics_reporting_scheduler.h

Index: components/metrics/metrics_reporting_scheduler.h
diff --git a/components/metrics/metrics_reporting_scheduler.h b/components/metrics/metrics_reporting_scheduler.h
index 7cdfad82b8309c4971cc4a4121e9d8985c915614..3e58aaaa21ceb498b8ef4b81b55202e82bb03fdc 100644
--- a/components/metrics/metrics_reporting_scheduler.h
+++ b/components/metrics/metrics_reporting_scheduler.h
@@ -11,6 +11,8 @@
 #include "base/time/time.h"
 #include "base/timer/timer.h"
 
+namespace metrics {
+
 // Scheduler task to drive a MetricsService object's uploading.
 class MetricsReportingScheduler {
  public:
@@ -75,4 +77,6 @@ class MetricsReportingScheduler {
   DISALLOW_COPY_AND_ASSIGN(MetricsReportingScheduler);
 };
 
+}  // namespace metrics
+
 #endif  // COMPONENTS_METRICS_METRICS_REPORTING_SCHEDULER_H_