Make MetricsService upload logs through an interface.

components/metrics/test_metrics_service_client.cc

Index: components/metrics/test_metrics_service_client.cc
===================================================================
--- components/metrics/test_metrics_service_client.cc	(revision 272759)
+++ components/metrics/test_metrics_service_client.cc	(working copy)
@@ -55,4 +55,11 @@
   done_callback.Run();
 }
 
+scoped_ptr<MetricsLogUploader> TestMetricsServiceClient::CreateUploader(
+    const std::string& server_url,
+    const std::string& mime_type,
+    const base::Callback<void(int)> on_upload_complete) {
+  return scoped_ptr<MetricsLogUploader>();
+}
+
 }  // namespace metrics