Update ui::PointerEvent to support mouse wheel and capture change events.

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 113 matching lines @@
   bool IsTouchEvent() const {
     return type_ == ET_TOUCH_RELEASED ||
            type_ == ET_TOUCH_PRESSED ||
            type_ == ET_TOUCH_MOVED ||
            type_ == ET_TOUCH_CANCELLED;
   }
 
   bool IsPointerEvent() const {
     return type_ == ET_POINTER_DOWN || type_ == ET_POINTER_MOVED ||
            type_ == ET_POINTER_UP || type_ == ET_POINTER_CANCELLED ||
-           type_ == ET_POINTER_ENTERED || type_ == ET_POINTER_EXITED;
+           type_ == ET_POINTER_ENTERED || type_ == ET_POINTER_EXITED ||
+           type_ == ET_POINTER_WHEEL_CHANGED ||
+           type_ == ET_POINTER_CAPTURE_CHANGED;
   }
 
   // Convenience methods to check pointer type of |this|. Returns false if
   // |this| is not a PointerEvent.
   bool IsMousePointerEvent() const;
   bool IsTouchPointerEvent() const;
 
   bool IsGestureEvent() const {
     switch (type_) {
       case ET_GESTURE_SCROLL_BEGIN:
@@ skipping 260 matching lines @@
                  float tilt_x,
                  float tilt_y)
       : pointer_type(pointer_type),
         // If we aren't provided with a radius on one axis, use the
         // information from the other axis.
         radius_x(radius_x > 0 ? radius_x : radius_y),
         radius_y(radius_y > 0 ? radius_y : radius_x),
         force(force),
         tilt_x(tilt_x),
         tilt_y(tilt_y) {}
+  PointerDetails(EventPointerType pointer_type, int offset_x, int offset_y)
+      : pointer_type(pointer_type),
+        force(std::numeric_limits<float>::quiet_NaN()),
+        offset_x(offset_x),
+        offset_y(offset_y) {}
 
   bool operator==(const PointerDetails& other) const {
-    return pointer_type == other.pointer_type &&
-           radius_x == other.radius_x &&
+    return pointer_type == other.pointer_type && radius_x == other.radius_x &&
            radius_y == other.radius_y &&
            (force == other.force ||
             (std::isnan(force) && std::isnan(other.force))) &&
-           tilt_x == other.tilt_x &&
-           tilt_y == other.tilt_y;
+           tilt_x == other.tilt_x && tilt_y == other.tilt_y &&
+           offset_x == other.offset_x && offset_y == other.offset_y;
   }
 
   // The type of pointer device.
   EventPointerType pointer_type = EventPointerType::POINTER_TYPE_UNKNOWN;
 
   // Radius of the X (major) axis of the touch ellipse. 0.0 if unknown.
   float radius_x = 0.0;
 
   // Radius of the Y (minor) axis of the touch ellipse. 0.0 if unknown.
   float radius_y = 0.0;
 
   // Force (pressure) of the touch. Normalized to be [0, 1] except NaN means
   // pressure is not supported by the input device.
   float force = 0.0;
 
   // Tilt of a pen/stylus from surface normal as plane angle in degrees, values
   // lie in [-90,90]. A positive tilt_x is to the right and a positive tilt_y
   // is towards the user. 0.0 if unknown.
   float tilt_x = 0.0;
   float tilt_y = 0.0;
+
+  // Only used by mouse wheel events. The amount to scroll. This is in multiples
+  // of kWheelDelta.
+  // Note: x_offset() > 0/y_offset() > 0 means scroll left/up.
+  int offset_x = 0;
+  int offset_y = 0;

[sadrul, 2016/08/19 04:18:27]

Maybe use a gfx::Vector2dF instead?

[riajiang, 2016/08/19 16:19:39]

Done.

 };
 
 class EVENTS_EXPORT MouseEvent : public LocatedEvent {
  public:
   explicit MouseEvent(const base::NativeEvent& native_event);
 
   // |pointer_event.IsMousePointerEvent()| must be true.
   explicit MouseEvent(const PointerEvent& pointer_event);
 
   // Create a new MouseEvent based on the provided model.
@@ skipping 252 matching lines @@
   bool should_remove_native_touch_id_mapping_;
 
   // Structure for holding pointer details for implementing PointerEvents API.
   PointerDetails pointer_details_;
 };
 
 class EVENTS_EXPORT PointerEvent : public LocatedEvent {
  public:
   static const int32_t kMousePointerId;
 
-  // Returns true if a PointerEvent can be constructed from the given mouse or
-  // touch event. For example, PointerEvent does not support ET_MOUSEWHEEL or
-  // ET_MOUSE_CAPTURE_CHANGED.
+  // Returns true if |event| is a MouseEvent or TouchEvent.

[sadrul, 2016/08/19 04:18:27]

Something more like: Returns true if a PointerEvent can be constructed from
|event|. Currently, only mouse and touch events can be converted to pointer
events.

[riajiang, 2016/08/19 16:19:39]

Done.

   static bool CanConvertFrom(const Event& event);
 
   PointerEvent(const PointerEvent& pointer_event);
   explicit PointerEvent(const MouseEvent& mouse_event);
   explicit PointerEvent(const TouchEvent& touch_event);
 
   PointerEvent(EventType type,
                const gfx::Point& location,
                const gfx::Point& root_location,
                int flags,
@@ skipping 273 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_