Support tap_count in ui::GestureProvider.

ui/events/gestures/gesture_provider_aura.h

Index: ui/events/gestures/gesture_provider_aura.h
diff --git a/ui/events/gestures/gesture_provider_aura.h b/ui/events/gestures/gesture_provider_aura.h
index b4a9dedf3a37d3359d5f43d0d32addd92ed32461..a255f2b8aa10f809450248a0026290cd83e91c41 100644
--- a/ui/events/gestures/gesture_provider_aura.h
+++ b/ui/events/gestures/gesture_provider_aura.h
@@ -36,6 +36,18 @@ class EVENTS_EXPORT GestureProviderAura : public GestureProviderClient {
   virtual void OnGestureEvent(const GestureEventData& gesture) OVERRIDE;
 
  private:
+  bool IsConsideredDoubleTap(const MotionEvent& previous_down,
+                             const base::TimeTicks previous_tap_time,
+                             const MotionEvent& current_down) const;
+
+  scoped_ptr<MotionEvent> current_down_event_;
+  scoped_ptr<MotionEvent> previous_down_event_;
+  base::TimeTicks previous_tap_time_;
+
+  // Counts the number of successive taps which occured within the double tap
+  // window. The current maximum is 3.
+  int tap_count_;
+
   GestureProviderAuraClient* client_;
   MotionEventAura pointer_state_;
   FilteredGestureProvider filtered_gesture_provider_;