Basic UkmService implementation

components/metrics_services_manager/metrics_services_manager.h

Index: components/metrics_services_manager/metrics_services_manager.h
diff --git a/components/metrics_services_manager/metrics_services_manager.h b/components/metrics_services_manager/metrics_services_manager.h
index 19245c140596ad6a1bc45bf9bb2e517382e6c148..4bfe18d73daa44e6ba04cc0f404ab221d690dfb4 100644
--- a/components/metrics_services_manager/metrics_services_manager.h
+++ b/components/metrics_services_manager/metrics_services_manager.h
@@ -25,6 +25,10 @@ namespace rappor {
 class RapporServiceImpl;
 }
 
+namespace ukm {
+class UkmService;
+}
+
 namespace variations {
 class VariationsService;
 }
@@ -60,6 +64,9 @@ class MetricsServicesManager {
   // Returns the RapporServiceImpl, creating it if it hasn't been created yet.
   rappor::RapporServiceImpl* GetRapporServiceImpl();
 
+  // Returns the UkmService, creating it if it hasn't been created yet.
+  ukm::UkmService* GetUkmService();
+
   // Returns the VariationsService, creating it if it hasn't been created yet.
   variations::VariationsService* GetVariationsService();