Print Preview: change getPreview to cr.sendWithPromise

chrome/browser/ui/webui/print_preview/print_preview_ui.h

Index: chrome/browser/ui/webui/print_preview/print_preview_ui.h
diff --git a/chrome/browser/ui/webui/print_preview/print_preview_ui.h b/chrome/browser/ui/webui/print_preview/print_preview_ui.h
index 2abe24e64a1dc61ee0ac4e134509471ad12fe53e..722c3168e2f8b510143fea1bf8aa4019ea4c701e 100644
--- a/chrome/browser/ui/webui/print_preview/print_preview_ui.h
+++ b/chrome/browser/ui/webui/print_preview/print_preview_ui.h
@@ -115,6 +115,9 @@ class PrintPreviewUI : public ConstrainedWebDialogUI {
   // closed, which may occur for several reasons, e.g. tab closure or crash.
   void OnPrintPreviewDialogClosed();
 
+  // Notifies the Web UI that the preview request was cancelled.
+  void OnPrintPreviewCancelled();
+
   // Notifies the Web UI that initiator is closed, so we can disable all the
   // controls that need the initiator for generating the preview data.
   void OnInitiatorClosed();