MacViews: Send Mac scrollWheel NSEvents as ui::ET_SCROLL (ui::ScrollEvent).

ui/events/cocoa/events_mac.mm

 // 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.
 
 #include "ui/events/event_utils.h"
 
 #include <Cocoa/Cocoa.h>
 #include <stdint.h>
 
 #include "base/logging.h"
@@ skipping 25 matching lines @@
     case NSRightMouseUp:
     case NSOtherMouseUp:
       return ET_MOUSE_RELEASED;
     case NSLeftMouseDragged:
     case NSRightMouseDragged:
     case NSOtherMouseDragged:
       return ET_MOUSE_DRAGGED;
     case NSMouseMoved:
       return ET_MOUSE_MOVED;
     case NSScrollWheel:
-      return ET_MOUSEWHEEL;
+      return ET_SCROLL;
     case NSMouseEntered:
       return ET_MOUSE_ENTERED;
     case NSMouseExited:
       return ET_MOUSE_EXITED;
     case NSEventTypeSwipe:
       return ET_SCROLL_FLING_START;
     case NSAppKitDefined:
     case NSSystemDefined:
       return ET_UNKNOWN;
     case NSFlagsChanged:
@@ skipping 134 matching lines @@
                         /* force */ 0.f,
                         /* tilt_x */ 0.f,
                         /* tilt_y */ 0.f);
 }
 
 bool GetScrollOffsets(const base::NativeEvent& native_event,
                       float* x_offset,
                       float* y_offset,
                       float* x_offset_ordinal,
                       float* y_offset_ordinal,
-                      int* finger_count) {
-  NOTIMPLEMENTED();
-  return false;
+                      int* finger_count,
+                      EventMomentumPhase* momentum_phase) {
+  gfx::Vector2d offset = GetMouseWheelOffset(native_event);
+  *x_offset = *x_offset_ordinal = offset.x();
+  *y_offset = *y_offset_ordinal = offset.y();
+
+  // For non-scrolling events, the finger count can be determined with
+  // [[native_event touchesMatchingPhase:NSTouchPhaseTouching inView:nil] count]
+  // but it's illegal to ask that of scroll events, so say two fingers.
+  *finger_count = 2;
+
+  // If a user just rests two fingers on the touchpad without moving, AppKit
+  // uses NSEventPhaseMayBegin. Treat this the same as NSEventPhaseBegan.
+  const NSUInteger kBeginPhaseMask = NSEventPhaseBegan | NSEventPhaseMayBegin;
+  const NSUInteger kEndPhaseMask = NSEventPhaseCancelled | NSEventPhaseEnded;
+
+  // Note: although the NSEventPhase constants are bit flags, the logic here
+  // assumes AppKit will not combine them, so momentum phase should only be set
+  // once. If one of these DCHECKs fails it could mean some new hardware that
+  // needs tests in events_mac_unittest.mm.
+  DCHECK_EQ(EventMomentumPhase::NONE, *momentum_phase);
+
+  if ([native_event phase] & kBeginPhaseMask)
+    *momentum_phase = EventMomentumPhase::MAY_BEGIN;
+
+  if (([native_event phase] | [native_event momentumPhase]) & kEndPhaseMask) {
+    DCHECK_EQ(EventMomentumPhase::NONE, *momentum_phase);
+    *momentum_phase = EventMomentumPhase::END;
+  } else if ([native_event momentumPhase] != NSEventPhaseNone) {
+    DCHECK_EQ(EventMomentumPhase::NONE, *momentum_phase);
+    *momentum_phase = EventMomentumPhase::INERTIAL_UPDATE;
+  }
+
+  // If the event completely lacks phase information, there won't be further
+  // updates, so they must be treated as an end.
+  if (([native_event phase] | [native_event momentumPhase]) ==
+      NSEventPhaseNone) {
+    DCHECK_EQ(EventMomentumPhase::NONE, *momentum_phase);
+    *momentum_phase = EventMomentumPhase::END;
+  }
+
+  return true;
 }
 
 bool GetFlingData(const base::NativeEvent& native_event,
                   float* vx,
                   float* vy,
                   float* vx_ordinal,
                   float* vy_ordinal,
                   bool* is_cancel) {
   NOTIMPLEMENTED();
   return false;
@@ skipping 47 matching lines @@
   uint16_t return_value;
   [text getCharacters:&return_value];
   return return_value;
 }
 
 bool IsCharFromNative(const base::NativeEvent& native_event) {
   return false;
 }
 
 }  // namespace ui