PrintPreview: Make ctrl-shift-p start the native print flow.

chrome/browser/ui/webui/print_preview_ui.h

Index: chrome/browser/ui/webui/print_preview_ui.h
diff --git a/chrome/browser/ui/webui/print_preview_ui.h b/chrome/browser/ui/webui/print_preview_ui.h
index ccd2e77f6eb8f0e0994c91698153377bdf396bbc..589f4414c79c6d8ddadde87675a2ba510291dd10 100644
--- a/chrome/browser/ui/webui/print_preview_ui.h
+++ b/chrome/browser/ui/webui/print_preview_ui.h
@@ -58,6 +58,9 @@ class PrintPreviewUI : public ChromeWebUI {
   // Notifies the Web UI of a print preview request with |request_id|.
   void OnPrintPreviewRequest(int request_id);
 
+  // Notifies the Web UI to show the system dialog.
+  void OnShowSystemDialog();
+
   // Notifies the Web UI about the page count of the request preview.
   void OnDidGetPreviewPageCount(
       const PrintHostMsg_DidGetPreviewPageCount_Params& params);
@@ -96,6 +99,9 @@ class PrintPreviewUI : public ChromeWebUI {
   // Notifies the Web UI renderer that file selection has been cancelled.
   void OnFileSelectionCancelled();
 
+  // Notifies the Web UI to cancel the pending preview request.
+  void OnCancelPendingPreviewRequest();
+
  private:
   FRIEND_TEST_ALL_PREFIXES(PrintPreviewTabControllerUnitTest,
                            TitleAfterReload);