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

ui/events/test/cocoa_test_event_utils.mm

Index: ui/events/test/cocoa_test_event_utils.mm
diff --git a/ui/events/test/cocoa_test_event_utils.mm b/ui/events/test/cocoa_test_event_utils.mm
index 490382553f4081b03a193865e0efc180b2ac9774..b225710adc61099936f04e5b7c03d0714c0481cb 100644
--- a/ui/events/test/cocoa_test_event_utils.mm
+++ b/ui/events/test/cocoa_test_event_utils.mm
@@ -135,18 +135,79 @@ std::pair<NSEvent*, NSEvent*> RightMouseClickInView(NSView* view,
   return std::make_pair(down, up);
 }
 
-NSEvent* TestScrollEvent(NSPoint location,
+NSEvent* TestScrollEvent(NSPoint window_point,
                          NSWindow* window,
                          CGFloat delta_x,
-                         CGFloat delta_y) {
+                         CGFloat delta_y,
+                         bool has_precise_deltas,
+                         NSEventPhase event_phase,
+                         NSEventPhase momentum_phase) {
   const uint32_t wheel_count = 2;
   int32_t wheel1 = static_cast<int>(delta_y);
   int32_t wheel2 = static_cast<int>(delta_x);
-  CGScrollEventUnit units = kCGScrollEventUnitLine;
+  CGScrollEventUnit units =
+      has_precise_deltas ? kCGScrollEventUnitPixel : kCGScrollEventUnitLine;
   base::ScopedCFTypeRef<CGEventRef> scroll(CGEventCreateScrollWheelEvent(
       nullptr, units, wheel_count, wheel1, wheel2));
-  CGEventSetLocation(scroll, ScreenPointFromWindow(location, window));
-  return AttachWindowToCGEvent(scroll, window);
+  CGEventSetLocation(scroll, ScreenPointFromWindow(window_point, window));
+
+  // Always set event flags, otherwise +[NSEvent eventWithCGEvent:] populates
+  // flags from current keyboard state which can make tests flaky.
+  CGEventSetFlags(scroll, 0);
+
+  if (has_precise_deltas) {
+    // kCGScrollWheelEventIsContinuous is -[NSEvent hasPreciseScrollingDeltas].
+    // CGEventTypes.h says it should be non-zero for pixel-based scrolling.
+    // Verify that CGEventCreateScrollWheelEvent() set it.
+    DCHECK_EQ(1, CGEventGetIntegerValueField(scroll,
+                                             kCGScrollWheelEventIsContinuous));
+  }
+
+  // Don't set phase information when neither.
+  if (event_phase != NSEventPhaseNone || momentum_phase != NSEventPhaseNone) {
+    // AppKit conflates CGScrollPhase (bitmask flags) and CGMomentumScrollPhase
+    // (an enum) into NSEventPhase, where it is used for both -[NSEvent phase]
+    // and -[NSEvent momentumPhase]. Do a reverse mapping here.
+    int cg_event_phase = 0;
+    if (event_phase & NSEventPhaseBegan)
+      cg_event_phase |= kCGScrollPhaseBegan;
+    if (event_phase & NSEventPhaseChanged)
+      cg_event_phase |= kCGScrollPhaseChanged;
+    if (event_phase & NSEventPhaseEnded)
+      cg_event_phase |= kCGScrollPhaseEnded;
+    if (event_phase & NSEventPhaseCancelled)
+      cg_event_phase |= kCGScrollPhaseCancelled;
+    if (event_phase & NSEventPhaseMayBegin)
+      cg_event_phase |= kCGScrollPhaseMayBegin;
+
+    CGMomentumScrollPhase cg_momentum_phase = kCGMomentumScrollPhaseNone;
+    switch (momentum_phase) {
+      case NSEventPhaseNone:
+        break;
+      case NSEventPhaseBegan:
+        cg_momentum_phase = kCGMomentumScrollPhaseBegin;
+        break;
+      case NSEventPhaseChanged:
+        cg_momentum_phase = kCGMomentumScrollPhaseContinue;
+        break;
+      case NSEventPhaseEnded:
+        cg_momentum_phase = kCGMomentumScrollPhaseEnd;
+        break;
+      default:
+        // Those are the only 4 options for CGMomentumScrollPhase. If something
+        // else was provided it should probably never appear on an NSEvent.
+        NOTREACHED();
+    }
+    CGEventSetIntegerValueField(scroll, kCGScrollWheelEventScrollPhase,
+                                cg_event_phase);
+    CGEventSetIntegerValueField(scroll, kCGScrollWheelEventMomentumPhase,
+                                cg_momentum_phase);
+  }
+  NSEvent* event = AttachWindowToCGEvent(scroll, window);
+  DCHECK_EQ(has_precise_deltas, [event hasPreciseScrollingDeltas]);
+  DCHECK_EQ(event_phase, [event phase]);
+  DCHECK_EQ(momentum_phase, [event momentumPhase]);
+  return event;
 }
 
 NSEvent* KeyEventWithCharacter(unichar c) {