Fix mouse wheel events processing.

ui/views/widget/widget_unittest.cc

Index: ui/views/widget/widget_unittest.cc
diff --git a/ui/views/widget/widget_unittest.cc b/ui/views/widget/widget_unittest.cc
index f7b3e691bfab6f6472f7a3e1a961d6472db4745b..b9bc154b15ad685964f49cf5c85b1ea39f83d7f3 100644
--- a/ui/views/widget/widget_unittest.cc
+++ b/ui/views/widget/widget_unittest.cc
@@ -3627,6 +3627,24 @@ TEST_F(WidgetTest, WidgetRemovalsObserverCalledWhenMovingBetweenWidgets) {
   widget->RemoveRemovalsObserver(&removals_observer);
 }
 
+TEST_F(WidgetTest, MouseWheelEvent) {

[tapted, 2016/10/30 23:54:46]

nit: tests should have a comment describing their purpose e.g. "// Test dispatch
of ui::ET_MOUSEWHEEL."

[snake, 2016/10/31 11:32:06]

Done.

+  Widget* widget = CreateTopLevelPlatformWidget();

[sadrul, 2016/10/29 05:52:54]

Like the tests above, use WidgetAutoclosePtr instead?

[snake, 2016/10/31 11:32:06]

Done.

+  widget->SetBounds(gfx::Rect(0, 0, 600, 600));
+  EventCountView* event_count_view = new EventCountView();
+  widget->GetContentsView()->AddChildView(event_count_view);
+  event_count_view->SetBounds(0, 0, 600, 600);
+  widget->Show();
+
+  ui::test::EventGenerator event_generator(GetContext(),
+                                           widget->GetNativeWindow());
+
+  event_generator.MoveMouseWheel(1, 1);
+  EXPECT_EQ(1, event_count_view->GetEventCount(ui::ET_MOUSEWHEEL));
+  event_count_view->ResetCounts();
+
+  widget->CloseNow();
+}
+
 #if defined(OS_WIN)
 
 namespace {