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

ui/events/event_utils.cc

 // 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.
 
 #include "ui/events/event_utils.h"
 
 #include <vector>
 
 #include "base/metrics/histogram_macros.h"
 #include "ui/display/display.h"
@@ skipping 92 matching lines @@
   return display::Display::TOUCH_SUPPORT_UNAVAILABLE;
 }
 
 void ComputeEventLatencyOS(const base::NativeEvent& native_event) {
   base::TimeTicks current_time = EventTimeForNow();
   base::TimeTicks time_stamp = EventTimeFromNative(native_event);
   base::TimeDelta delta = current_time - time_stamp;
 
   EventType type = EventTypeFromNative(native_event);
   switch (type) {
+#if defined(OS_MACOSX)
+    // On Mac, ET_SCROLL and ET_MOUSEWHEEL represent the same class of events.
+    case ET_SCROLL:
+#endif
     case ET_MOUSEWHEEL:
       UMA_HISTOGRAM_CUSTOM_COUNTS("Event.Latency.OS.MOUSE_WHEEL",
                                   delta.InMicroseconds(), 1, 1000000, 50);
       return;
     case ET_TOUCH_MOVED:
       UMA_HISTOGRAM_CUSTOM_COUNTS("Event.Latency.OS.TOUCH_MOVED",
                                   delta.InMicroseconds(), 1, 1000000, 50);
       return;
     case ET_TOUCH_PRESSED:
       UMA_HISTOGRAM_CUSTOM_COUNTS("Event.Latency.OS.TOUCH_PRESSED",
                                   delta.InMicroseconds(), 1, 1000000, 50);
       return;
     case ET_TOUCH_RELEASED:
       UMA_HISTOGRAM_CUSTOM_COUNTS("Event.Latency.OS.TOUCH_RELEASED",
                                   delta.InMicroseconds(), 1, 1000000, 50);
       return;
     default:
       return;
   }
 }
 
 }  // namespace ui