Merge 245651 "Add support for horizontal mouse wheel messages in..."

ui/events/win/events_win.cc

Index: ui/events/win/events_win.cc
===================================================================
--- ui/events/win/events_win.cc	(revision 246169)
+++ ui/events/win/events_win.cc	(working copy)
@@ -180,6 +180,7 @@
     case WM_NCMOUSEMOVE:
       return ET_MOUSE_MOVED;
     case WM_MOUSEWHEEL:
+    case WM_MOUSEHWHEEL:
       return ET_MOUSEWHEEL;
     case WM_MOUSELEAVE:
     case WM_NCMOUSELEAVE:
@@ -268,8 +269,11 @@
 }
 
 gfx::Vector2d GetMouseWheelOffset(const base::NativeEvent& native_event) {
-  DCHECK(native_event.message == WM_MOUSEWHEEL);
-  return gfx::Vector2d(0, GET_WHEEL_DELTA_WPARAM(native_event.wParam));
+  DCHECK(native_event.message == WM_MOUSEWHEEL ||
+         native_event.message == WM_MOUSEHWHEEL);
+  if (native_event.message == WM_MOUSEWHEEL)
+    return gfx::Vector2d(0, GET_WHEEL_DELTA_WPARAM(native_event.wParam));
+  return gfx::Vector2d(GET_WHEEL_DELTA_WPARAM(native_event.wParam), 0);
 }
 
 void ClearTouchIdIfReleased(const base::NativeEvent& xev) {