Support tap_count in ui::GestureProvider.

ui/events/gestures/gesture_provider_aura.h

 // Copyright 2014 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_EVENTS_GESTURE_DETECTION_UI_GESTURE_PROVIDER_H_
 #define UI_EVENTS_GESTURE_DETECTION_UI_GESTURE_PROVIDER_H_
 
 #include "base/basictypes.h"
 #include "ui/events/event.h"
 #include "ui/events/events_export.h"
@@ skipping 18 matching lines @@
   virtual ~GestureProviderAura();
 
   bool OnTouchEvent(const TouchEvent& event);
   void OnTouchEventAck(bool event_consumed);
   const MotionEventAura& pointer_state() { return pointer_state_; }
 
   // GestureProviderClient implementation
   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_;
 
   int last_touch_event_flags_;
 
   DISALLOW_COPY_AND_ASSIGN(GestureProviderAura);
 };
 
 }  // namespace ui
 
 #endif  // UI_EVENTS_GESTURE_DETECTION_UI_GESTURE_PROVIDER_H_