downloads: Improve download rate estimation.

content/browser/download/download_file_impl.cc

Index: content/browser/download/download_file_impl.cc
diff --git a/content/browser/download/download_file_impl.cc b/content/browser/download/download_file_impl.cc
index 9c064d20c4edb9003eb6fc74fe782a8be9db49b7..1c0b384cbeabe81034219b2dc4ae04abd8094963 100644
--- a/content/browser/download/download_file_impl.cc
+++ b/content/browser/download/download_file_impl.cc
@@ -98,6 +98,7 @@ DownloadInterruptReason DownloadFileImpl::AppendDataToFile(
                          base::TimeDelta::FromMilliseconds(kUpdatePeriodMs),
                          this, &DownloadFileImpl::SendUpdate);
   }
+  rate_estimator_.Increment(data_len);
   return file_.AppendDataToFile(data, data_len);
 }
 
@@ -191,7 +192,7 @@ int64 DownloadFileImpl::BytesSoFar() const {
 }
 
 int64 DownloadFileImpl::CurrentSpeed() const {
-  return file_.CurrentSpeed();
+  return rate_estimator_.GetCountPerSecond();
 }
 
 bool DownloadFileImpl::GetHash(std::string* hash) {