Print Preview: Display a throbber when the user requests the system print

chrome/browser/printing/print_view_manager_delegate.h

+// Copyright (c) 2011 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.
+
+#ifndef CHROME_BROWSER_PRINTING_PRINT_VIEW_MANAGER_DELEGATE_H_
+#define CHROME_BROWSER_PRINTING_PRINT_VIEW_MANAGER_DELEGATE_H_
+#pragma once
+
+namespace printing {
+
+// Interface for interaction between the PrintViewManager and a delegate.
+class PrintViewManagerDelegate {
+ public:
+  // Notifies the delegate that the print dialog was shown.
+  virtual void OnPrintDialogShown() = 0;
+
+ protected:
+  virtual ~PrintViewManagerDelegate() {}
+};
+
+}  // namespace printing
+
+#endif  // CHROME_BROWSER_PRINTING_PRINT_VIEW_MANAGER_DELEGATE_H_