Print preview not showing if default print is invalid.

chrome/renderer/mock_printer.cc

Index: chrome/renderer/mock_printer.cc
diff --git a/chrome/renderer/mock_printer.cc b/chrome/renderer/mock_printer.cc
index 3d1455911d9628cff9cc4550ee3ee14aa29ef782..79f9d9106a20f3e8774d4f7c046a42a98eefb39f 100644
--- a/chrome/renderer/mock_printer.cc
+++ b/chrome/renderer/mock_printer.cc
@@ -87,6 +87,12 @@ void MockPrinter::SetDefaultPrintSettings(const PrintMsg_Print_Params& params) {
   url_ = params.url;
 }
 
+void MockPrinter::UseInvalidSettings() {
+  use_invalid_settings_ = true;
+  PrintMsg_Print_Params empty_param;
+  SetDefaultPrintSettings(empty_param);
+}
+
 void MockPrinter::ScriptedPrint(int cookie,
                                 int expected_pages_count,
                                 bool has_selection,
@@ -236,7 +242,7 @@ bool MockPrinter::SaveBitmap(
 }
 
 int MockPrinter::CreateDocumentCookie() {
-  return ++current_document_cookie_;
+  return use_invalid_settings_ ? 0 : ++current_document_cookie_;
 }
 
 void MockPrinter::SetPrintParams(PrintMsg_Print_Params* params) {