Add a browser test that can communicate with the layout test framework and print pdfs.

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

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/webui/print_preview/print_preview_ui.h"
 
 #include <map>
 
 #include "base/id_map.h"
 #include "base/lazy_instance.h"
@@ skipping 592 matching lines @@
 }
 
 void PrintPreviewUI::OnPrintPreviewScalingDisabled() {
   web_ui()->CallJavascriptFunction("printScalingDisabledForSourcePDF");
 }
 
 // static
 void PrintPreviewUI::SetDelegateForTesting(TestingDelegate* delegate) {
   g_testing_delegate = delegate;
 }
+
+void PrintPreviewUI::SetSelectedFileForTesting(
+    const base::FilePath& path, int index, void* params) {
+  handler_->FileSelected(path, index, params);
+}