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

chrome/browser/metrics/metrics_services_manager.h

Index: chrome/browser/metrics/metrics_services_manager.h
diff --git a/chrome/browser/metrics/metrics_services_manager.h b/chrome/browser/metrics/metrics_services_manager.h
index 66d0c2a8fae36d829a9b76c83d5bcb23c195e230..5def2c41f7e9d6104cd5bfe99d9b071a6215e203 100644
--- a/chrome/browser/metrics/metrics_services_manager.h
+++ b/chrome/browser/metrics/metrics_services_manager.h
@@ -8,6 +8,7 @@
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/threading/thread_checker.h"
+#include "chrome/browser/metrics/chrome_metrics_service_client.h"
 
 class MetricsService;
 class PrefService;
@@ -54,6 +55,10 @@ class MetricsServicesManager {
   // MetricsStateManager which is passed as a parameter to service constructors.
   scoped_ptr<metrics::MetricsStateManager> metrics_state_manager_;
 
+  // Chrome embedder implementation of the MetricsServiceClient, which is passed
+  // as a parameter to the MetricsService.
+  ChromeMetricsServiceClient metrics_service_client_;
+
   // The MetricsService, used for UMA report uploads.
   scoped_ptr<MetricsService> metrics_service_;