Support 3f swipe for tab scrubbing

ui/base/events/event_utils.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 UI_BASE_EVENTS_EVENT_UTILS_H_
 #define UI_BASE_EVENTS_EVENT_UTILS_H_
 
 #include "base/event_types.h"
 #include "ui/base/events/event_constants.h"
 #include "ui/base/keycodes/keyboard_codes.h"
@@ skipping 74 matching lines @@
 UI_EXPORT float GetTouchForce(const base::NativeEvent& native_event);
 
 // Gets the fling velocity from a native event. is_cancel is set to true if
 // this was a tap down, intended to stop an ongoing fling.
 UI_EXPORT bool GetFlingData(const base::NativeEvent& native_event,
                             float* vx,
                             float* vy,
                             bool* is_cancel);
 
 // Returns whether this is a scroll event and optionally gets the amount to be
-// scrolled. |x_offset| and |y_offset| can be NULL.
+// scrolled. |x_offset|, |y_offset| and |finger_count| can be NULL.
 UI_EXPORT bool GetScrollOffsets(const base::NativeEvent& native_event,
                                 float* x_offset,
-                                float* y_offset);
+                                float* y_offset,
+                                int* finger_count);
 
 UI_EXPORT bool GetGestureTimes(const base::NativeEvent& native_event,
                                double* start_time,
                                double* end_time);
 
 // Enable/disable natural scrolling for touchpads.
 UI_EXPORT void SetNaturalScroll(bool enabled);
 
 // In natural scrolling enabled for touchpads?
 UI_EXPORT bool IsNaturalScrollEnabled();
@@ skipping 21 matching lines @@
 // Returns true if default post-target handling was canceled for |event| after
 // its dispatch to its target.
 UI_EXPORT bool EventCanceledDefaultHandling(const Event& event);
 
 // Registers a custom event type.
 UI_EXPORT int RegisterCustomEventType();
 
 }  // namespace ui
 
 #endif  // UI_BASE_EVENTS_EVENT_UTILS_H_