Use StringPiece for CreateUploader/NetMetricsLogUploader params.

android_webview/native/aw_metrics_service_client_impl.h

Index: android_webview/native/aw_metrics_service_client_impl.h
diff --git a/android_webview/native/aw_metrics_service_client_impl.h b/android_webview/native/aw_metrics_service_client_impl.h
index 6d42f1de47d56af4ff488cfc1bc01c6d231b1759..ab44b83ad91720409f45dbd912422df28643cf42 100644
--- a/android_webview/native/aw_metrics_service_client_impl.h
+++ b/android_webview/native/aw_metrics_service_client_impl.h
@@ -54,8 +54,8 @@ class AwMetricsServiceClientImpl : public AwMetricsServiceClient {
       const base::Closure& done_callback) override;
   void CollectFinalMetricsForLog(const base::Closure& done_callback) override;
   std::unique_ptr<metrics::MetricsLogUploader> CreateUploader(
-      const std::string& server_url,
-      const std::string& mime_type,
+      base::StringPiece server_url,
+      base::StringPiece mime_type,
       metrics::MetricsLogUploader::MetricServiceType service_type,
       const base::Callback<void(int)>& on_upload_complete) override;
   base::TimeDelta GetStandardUploadInterval() override;