Dispatch transfer size update notification on mojo-loading

content/common/url_loader.mojom

Index: content/common/url_loader.mojom
diff --git a/content/common/url_loader.mojom b/content/common/url_loader.mojom
index f77988b238bd2d74a1d6a29e8b682de11ce9bec8..4e92378ac41818a649cae703feb802d1aae752dc 100644
--- a/content/common/url_loader.mojom
+++ b/content/common/url_loader.mojom
@@ -44,8 +44,20 @@ interface URLLoaderClient {
   // Called when some data from a resource request has been downloaded to the
   // file. This is only called in the 'download_to_file' case and replaces
   // OnStartLoadingResponseBody in the call sequence in that case.
+  // TODO(yhirano): Remove |encoded_length| and use OnTransferSizeUpdated
+  // instead.
   OnDataDownloaded(int64 data_length, int64 encoded_length);
 
+  // Called when the transfer size is updated. This is only called if
+  // |report_raw_headers| is set and |download_to_file| is unset in the request.
+  // The transfer size is the length of the response (including both headers
+  // and the body) over the network. |transfer_size_diff| is the difference from
+  // the value previously reported one (including the one in OnReceiveResponse
+  // and OnReceiveRedirect). It must be positive.
+  // TODO(yhirano): Dispatch this notification even when |download_to_file| is
+  // set.
+  OnTransferSizeUpdated(int64 transfer_size_diff);
+
   // Called when the loader starts loading response body.
   OnStartLoadingResponseBody(handle<data_pipe_consumer> body);