Cancel the pending print preview request when the user request to show the system dialog.

chrome/browser/ui/webui/print_preview_ui.cc

Index: chrome/browser/ui/webui/print_preview_ui.cc
diff --git a/chrome/browser/ui/webui/print_preview_ui.cc b/chrome/browser/ui/webui/print_preview_ui.cc
index 7e087e67ba34387e1336c419f1848c64a277fc90..d2b2ae008e4114c8388729c8ffa5ff40f8686105 100644
--- a/chrome/browser/ui/webui/print_preview_ui.cc
+++ b/chrome/browser/ui/webui/print_preview_ui.cc
@@ -219,6 +219,10 @@ void PrintPreviewUI::OnFileSelectionCancelled() {
   CallJavascriptFunction("fileSelectionCancelled");
 }
 
+void PrintPreviewUI::OnCancelPendingPreviewRequest() {
+  g_print_preview_request_id_map.Get().Set(preview_ui_addr_str_, -1);
+}
+
 void PrintPreviewUI::OnPrintPreviewFailed() {
   CallJavascriptFunction("printPreviewFailed");
 }