MacViews: Reveal scrollbars when resting on the trackpad.

ui/events/event.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_EVENTS_EVENT_H_
 #define UI_EVENTS_EVENT_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 955 matching lines @@
 
   // Used for tests.
   ScrollEvent(EventType type,
               const gfx::Point& location,
               base::TimeTicks time_stamp,
               int flags,
               float x_offset,
               float y_offset,
               float x_offset_ordinal,
               float y_offset_ordinal,
-              int finger_count);
+              int finger_count,
+              EventMomentumPhase momentum_phase = EventMomentumPhase::NONE);
 
   // Scale the scroll event's offset value.
   // This is useful in the multi-monitor setup where it needs to be scaled
   // to provide a consistent user experience.
   void Scale(const float factor);
 
   float x_offset() const { return x_offset_; }
   float y_offset() const { return y_offset_; }
   float x_offset_ordinal() const { return x_offset_ordinal_; }
   float y_offset_ordinal() const { return y_offset_ordinal_; }
@@ skipping 50 matching lines @@
   // dispatched. This field gets a non-zero value only for gestures that are
   // released through TouchDispositionGestureFilter::SendGesture. The gesture
   // events that aren't fired directly in response to processing a touch-event
   // (e.g. timer fired ones), this id is zero. See crbug.com/618738.
   uint32_t unique_touch_event_id_;
 };
 
 }  // namespace ui
 
 #endif  // UI_EVENTS_EVENT_H_