Don't track mouse events in HWNDMessageHandler when they are forwarded by the LegacyRenderWidgetHost

ui/views/win/hwnd_message_handler.cc

Index: ui/views/win/hwnd_message_handler.cc
===================================================================
--- ui/views/win/hwnd_message_handler.cc	(revision 250790)
+++ ui/views/win/hwnd_message_handler.cc	(working copy)
@@ -1022,6 +1022,10 @@
     // clear restore_focus_when_enabled_.
     restore_focus_when_enabled_ = false;
     delegate_->SaveFocusOnDeactivate();
+    // When we lose activation send a dummy WM_MOUSELEAVE message. This is to
+    // handle cases when we don't track certain WM_MOUSEMOVE messages like those
+    // coming from a child.
+    ::PostMessage(hwnd(), WM_MOUSELEAVE, 0, 0);

[sky, 2014/02/12 22:51:29]

If the legacy hwnd starts tracking mouse events, is this necessary any longer?

[ananta, 2014/02/12 23:17:08]

When it does. The TrackMouseEvent API succeeds on the legacy hwnd, but fails to
track the mouse. Until then this is necessary.

   } else {
     // We must restore the focus after the message has been DefProc'ed as it
     // does set the focus to the last focused HWND.
@@ -1628,7 +1632,6 @@
     // be WM_RBUTTONUP instead of WM_NCRBUTTONUP.
     SetCapture();
   }
-
   MSG msg = { hwnd(), message, w_param, l_param, GetMessageTime(),
               { CR_GET_X_LPARAM(l_param), CR_GET_Y_LPARAM(l_param) } };
   ui::MouseEvent event(msg);
@@ -1638,7 +1641,8 @@
   if (!(event.flags() & ui::EF_IS_NON_CLIENT))
     delegate_->HandleTooltipMouseMove(message, w_param, l_param);
 
-  if (event.type() == ui::ET_MOUSE_MOVED && !HasCapture()) {
+  if (event.type() == ui::ET_MOUSE_MOVED && !HasCapture() &&
+      HIWORD(w_param) != SPECIAL_MOUSEMOVE_NOT_TO_BE_TRACKED) {

[sky, 2014/02/12 22:51:29]

Does this imply we need to track mouse mouse events in the child? If we don't,
doesn't that mean we may miss an exit?

[ananta, 2014/02/12 23:17:08]

When the mouse leaves the bounds of the child we would get a WM_NCMOUSEMOVE or a
WM_MOUSEMOVE depending on where we would go. That should get us a WM_MOUSELEAVE.
Additionally if we lose activation we have a dummy WM_MOUSELEAVE posted to cover
for this.

     // Windows only fires WM_MOUSELEAVE events if the application begins
     // "tracking" mouse events for a given HWND during WM_MOUSEMOVE events.
     // We need to call |TrackMouseEvents| to listen for WM_MOUSELEAVE.