Pass MetricsServiceClient into MetricsService, and create a simple stubbed TestMetricsServiceClient…

chrome/browser/metrics/metrics_services_manager.cc

Index: chrome/browser/metrics/metrics_services_manager.cc
diff --git a/chrome/browser/metrics/metrics_services_manager.cc b/chrome/browser/metrics/metrics_services_manager.cc
index 002f18383235aebe6ef0c5202704345f570b54c1..4c7fbe0fef527d73ac8928ea79d9dbce22c93d86 100644
--- a/chrome/browser/metrics/metrics_services_manager.cc
+++ b/chrome/browser/metrics/metrics_services_manager.cc
@@ -19,8 +19,10 @@ MetricsServicesManager::~MetricsServicesManager() {
 
 MetricsService* MetricsServicesManager::GetMetricsService() {
   DCHECK(thread_checker_.CalledOnValidThread());
-  if (!metrics_service_)
-    metrics_service_.reset(new MetricsService(GetMetricsStateManager()));
+  if (!metrics_service_) {
+    metrics_service_.reset(
+      new MetricsService(GetMetricsStateManager(), &metrics_service_client_));
+  }
   return metrics_service_.get();
 }