PrintPreview: Preview generation should not block print button.

chrome/browser/printing/print_preview_message_handler.cc

Index: chrome/browser/printing/print_preview_message_handler.cc
diff --git a/chrome/browser/printing/print_preview_message_handler.cc b/chrome/browser/printing/print_preview_message_handler.cc
index d293d6f1d6e2829f2f43e1e7e3964fb66a627179..8244c9f04320e6a71e63a53eb987203bd8a4371a 100644
--- a/chrome/browser/printing/print_preview_message_handler.cc
+++ b/chrome/browser/printing/print_preview_message_handler.cc
@@ -114,7 +114,19 @@ void PrintPreviewMessageHandler::OnPrintPreviewFailed(int document_cookie) {
   // User might have closed it already.
   if (!print_preview_tab)
     return;
-  print_preview_tab->web_ui()->CallJavascriptFunction("printPreviewFailed");
+
+  PrintPreviewUI* print_preview_ui =
+      static_cast<PrintPreviewUI*>(print_preview_tab->web_ui());
+
+  if (print_preview_ui->isHidden()) {
+    // Preview tab was hidden to serve the print request.
+    RenderViewHost* rvh = tab_contents()->render_view_host();
+    rvh->Send(new PrintMsg_PrintingDone(rvh->routing_id(), false));
+    delete print_preview_tab;
+    return;
+  } else {
+    print_preview_ui->CallJavascriptFunction("printPreviewFailed");
+  }
 }
 
 bool PrintPreviewMessageHandler::OnMessageReceived(