[src/content] Apply automatic range checks to enum types across IPC .

content/common/navigation_gesture.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 CONTENT_COMMON_NAVIGATION_GESTURE_H_
 #define CONTENT_COMMON_NAVIGATION_GESTURE_H_
 
 namespace content {
 
 enum NavigationGesture {
   // User initiated navigation/load.
   NavigationGestureUser,
   // Non-user initiated navigation/load. For example, onload- or
   // setTimeout-triggered document.location changes and form.submits.  See
   // http://b/1046841 for some cases that should be treated this way but aren't.
   NavigationGestureAuto,
   // Initial state.
   NavigationGestureUnknown,
+
+  NavigationGestureLast = NavigationGestureUnknown
+
 };
 
 }  // namespace content
 
 #endif  // CONTENT_COMMON_NAVIGATION_GESTURE_H_