Use StringPiece for CreateUploader/NetMetricsLogUploader params.

components/metrics/test_metrics_log_uploader.h

Index: components/metrics/test_metrics_log_uploader.h
diff --git a/components/metrics/test_metrics_log_uploader.h b/components/metrics/test_metrics_log_uploader.h
index 196370a4198993e969d6b835647e316bab24c3c5..abc43cce0cdf19ca477b240d92c1677f7724b0e5 100644
--- a/components/metrics/test_metrics_log_uploader.h
+++ b/components/metrics/test_metrics_log_uploader.h
@@ -11,10 +11,8 @@ namespace metrics {
 
 class TestMetricsLogUploader : public MetricsLogUploader {
  public:
-  TestMetricsLogUploader(const std::string& server_url,
-                         const std::string& mime_type,
-                         MetricsLogUploader::MetricServiceType service_type,
-                         const base::Callback<void(int)>& on_upload_complete);
+  explicit TestMetricsLogUploader(
+      const base::Callback<void(int)>& on_upload_complete);
   ~TestMetricsLogUploader() override;
 
   // Mark the current upload complete with the given response code.
@@ -28,6 +26,7 @@ class TestMetricsLogUploader : public MetricsLogUploader {
   void UploadLog(const std::string& compressed_log_data,
                  const std::string& log_hash) override;
 
+  const base::Callback<void(int)> on_upload_complete_;
   bool is_uploading_;
 
   DISALLOW_COPY_AND_ASSIGN(TestMetricsLogUploader);