Add the prototype for the function to display metro style notifications.

base/win/metro.h

 // 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.
 
 #ifndef BASE_WIN_METRO_H_
 #define BASE_WIN_METRO_H_
 
 #include <windows.h>
 #include <wpcapi.h>
 
@@ skipping 52 matching lines @@
 BASE_EXPORT bool IsTouchEnabled();
 
 // Returns true if Windows Parental control activity logging is enabled. This
 // feature is available on Windows Vista and beyond.
 // This function should ideally be called on the UI thread.
 BASE_EXPORT bool IsParentalControlActivityLoggingOn();
 
 // Handler function for the buttons on a metro dialog box
 typedef void (*MetroDialogButtonPressedHandler)();
 
+// Function to display metro style notifications.
+typedef void (*MetroNotification)(const char* origin_url,
+                                  const char* icon_url,
+                                  const wchar_t* title,
+                                  const wchar_t* body,
+                                  const wchar_t* display_source,
+                                  const char* notification_id);
+
+
 }  // namespace win
 }  // namespace base
 
 #endif  // BASE_WIN_METRO_H_