Ensure that trackpad and trackpoint scrolling works on Windows desktop Aura with legacy trackpad dr…

ui/events/win/events_win.cc

Index: ui/events/win/events_win.cc
===================================================================
--- ui/events/win/events_win.cc	(revision 244237)
+++ ui/events/win/events_win.cc	(working copy)
@@ -90,6 +90,11 @@
          native_event.message == WM_SYSKEYUP;
 }
 
+bool IsScrollEvent(const base::NativeEvent& native_event) {
+  return native_event.message == WM_VSCROLL ||
+         native_event.message == WM_HSCROLL;
+}
+
 // Returns a mask corresponding to the set of pressed modifier keys.
 // Checks the current global state and the state sent by client mouse messages.
 int KeyStateFlagsFromNative(const base::NativeEvent& native_event) {
@@ -179,6 +184,9 @@
     case WM_MOUSELEAVE:
     case WM_NCMOUSELEAVE:
       return ET_MOUSE_EXITED;
+    case WM_VSCROLL:
+    case WM_HSCROLL:
+      return ET_SCROLL;
     default:
       // We can't NOTREACHED() here, since this function can be called for any
       // message.
@@ -206,11 +214,16 @@
   if (IsClientMouseEvent(native_event) && !IsMouseWheelEvent(native_event))
     return gfx::Point(native_event.lParam);
   DCHECK(IsNonClientMouseEvent(native_event) ||
-         IsMouseWheelEvent(native_event));
-  // Non-client message. The position is contained in a POINTS structure in
-  // LPARAM, and is in screen coordinates so we have to convert to client.
-  POINT native_point = { GET_X_LPARAM(native_event.lParam),
-                         GET_Y_LPARAM(native_event.lParam) };
+         IsMouseWheelEvent(native_event) || IsScrollEvent(native_event));
+  POINT native_point;
+  if (IsScrollEvent(native_event)) {
+    ::GetCursorPos(&native_point);
+  } else {
+    // Non-client message. The position is contained in a POINTS structure in
+    // LPARAM, and is in screen coordinates so we have to convert to client.
+    native_point.x = GET_X_LPARAM(native_event.lParam);
+    native_point.y = GET_Y_LPARAM(native_event.lParam);
+  }
   ScreenToClient(native_event.hwnd, &native_point);
   gfx::Point location(native_point);
   location = gfx::win::ScreenToDIPPoint(location);
@@ -294,8 +307,10 @@
                       float* x_offset_ordinal,
                       float* y_offset_ordinal,
                       int* finger_count) {
-  // Not supported in Windows.
-  NOTIMPLEMENTED();
+  // TODO(ananta)
+  // Support retrieving the scroll offsets from the scroll event.
+  if (native_event.message == WM_VSCROLL || native_event.message == WM_HSCROLL)
+    return true;
   return false;
 }