[Android] Use DIP coordinates with MotionEventAndroid

ui/events/gesture_detection/snap_scroll_controller.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_SNAP_SCROLL_CONTROLLER_H_
 #define UI_EVENTS_GESTURE_DETECTION_SNAP_SCROLL_CONTROLLER_H_
 
 #include "base/basictypes.h"
 #include "ui/events/gesture_detection/gesture_detection_export.h"
 
+namespace gfx {
+class Display;
+}
+
 namespace ui {
 
 class MotionEvent;
 class ZoomManager;
 
 // Port of SnapScrollController.java from Chromium
 // Controls the scroll snapping behavior based on scroll updates.
 class SnapScrollController {
  public:
-  struct GESTURE_DETECTION_EXPORT Config {
-    Config();
-    ~Config();
-    int screen_width_pixels;
-    int screen_height_pixels;
-    float device_scale_factor;
-  };
-
-  explicit SnapScrollController(const Config& config);
+  explicit SnapScrollController(const gfx::Display& display);
   ~SnapScrollController();
 
   // Updates the snap scroll mode based on the given X and Y distance to be
   // moved on scroll.  If the scroll update is above a threshold, the snapping
   // behavior is reset.
   void UpdateSnapScrollMode(float distance_x, float distance_y);
 
   // Sets the snap scroll mode based on the event type.
   void SetSnapScrollingMode(const MotionEvent& event,
                             bool is_scale_gesture_detection_in_progress);
 
   void ResetSnapScrollMode() { snap_scroll_mode_ = SNAP_NONE; }
   bool IsSnapVertical() const { return snap_scroll_mode_ == SNAP_VERT; }
   bool IsSnapHorizontal() const { return snap_scroll_mode_ == SNAP_HORIZ; }
   bool IsSnappingScrolls() const { return snap_scroll_mode_ != SNAP_NONE; }
 
  private:
   enum SnapMode {
     SNAP_NONE,
     SNAP_HORIZ,
     SNAP_VERT
   };
 
-  static float CalculateChannelDistance(const Config& config);
-
   float channel_distance_;
   SnapMode snap_scroll_mode_;
   float first_touch_x_;
   float first_touch_y_;
   float distance_x_;
   float distance_y_;
 
   DISALLOW_COPY_AND_ASSIGN(SnapScrollController);
 };
 
 }  // namespace ui
 
 #endif  // UI_EVENTS_GESTURE_DETECTION_SNAP_SCROLL_CONTROLLER_H_