Adding metrics logging for Simplified Gesture Navigation.

content/browser/web_contents/aura/types.h

 // Copyright 2017 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_BROWSER_WEB_CONTENTS_AURA_TYPES_H_
+#define CONTENT_BROWSER_WEB_CONTENTS_AURA_TYPES_H_
+
+#include "content/browser/renderer_host/overscroll_controller.h"
+
 namespace content {
 
+enum class NavigationDirection { NONE, FORWARD, BACK, NAVIGATION_COUNT };
+
 // Note that this enum is used to back an UMA histogram, so it should be
 // treated as append-only.
 enum UmaNavigationType {
   NAVIGATION_TYPE_NONE,
   FORWARD_TOUCHPAD,
   BACK_TOUCHPAD,
   FORWARD_TOUCHSCREEN,
   BACK_TOUCHSCREEN,
   NAVIGATION_TYPE_COUNT,
 };
 
+UmaNavigationType GetUmaNavigationType(NavigationDirection direction,
+                                       OverscrollSource source);
+
 }  // namespace content
+
+#endif  // CONTENT_BROWSER_WEB_CONTENTS_AURA_TYPES_H_