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

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 7f32261dad683cb41ea074ec27d46de9b11e7d86..fddb1f63baed86384444b5bb44f91d625db11ee0 100644
--- a/chrome/browser/ui/webui/print_preview/print_preview_ui.h
+++ b/chrome/browser/ui/webui/print_preview/print_preview_ui.h
@@ -19,6 +19,7 @@ struct PrintHostMsg_RequestPrintPreview_Params;
 
 namespace base {
 class RefCountedBytes;
+class FilePath;

[Lei Zhang, 2014/07/17 21:08:16]

nit: Alphabetical order.

[ivandavid, 2014/07/17 22:27:47]

Done.

 }
 
 namespace gfx {
@@ -58,7 +59,6 @@ class PrintPreviewUI : public ConstrainedWebDialogUI {
   base::string16 initiator_title() { return initiator_title_; }
 
   bool source_is_modifiable() { return source_is_modifiable_; }
-
   bool source_has_selection() { return source_has_selection_; }
 
   bool print_selection_only() { return print_selection_only_; }
@@ -154,6 +154,10 @@ class PrintPreviewUI : public ConstrainedWebDialogUI {
 
   static void SetDelegateForTesting(TestingDelegate* delegate);
 
+  // Allows for tests to set a file path to print a PDF to. This also initiates
+  // the printing without having to click a button on the print preview dialog.
+  void SetSelectedFileForTesting(const base::FilePath& path);
+
  private:
   friend class PrintPreviewHandlerTest;
   FRIEND_TEST_ALL_PREFIXES(PrintPreviewHandlerTest, StickyMarginsCustom);