Fix showing the sibling menu on mouse move

ash/display/screen_ash.cc

 // Copyright 2014 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 "ash/display/screen_ash.h"
 
 #include "ash/common/shelf/shelf_widget.h"
 #include "ash/common/wm/root_window_finder.h"
 #include "ash/common/wm_window.h"
 #include "ash/display/window_tree_host_manager.h"
@@ skipping 86 matching lines @@
 gfx::NativeWindow ScreenAsh::GetWindowAtScreenPoint(const gfx::Point& point) {
   aura::Window* root_window =
       WmWindow::GetAuraWindow(wm::GetRootWindowAt(point));
   aura::client::ScreenPositionClient* position_client =
       aura::client::GetScreenPositionClient(root_window);
 
   gfx::Point local_point = point;
   if (position_client)
     position_client->ConvertPointFromScreen(root_window, &local_point);
 
-  return root_window->GetTopWindowContainingPoint(local_point);

[afakhry, 2017/03/21 17:35:47]

+Sadrul.

Oshima and talked about deprecating this GetTopWindowContainingPoint() as it is
not used in many places but we want to confirm that its use here in this context
is wrong. WDYT?

[sadrul, 2017/03/22 20:04:31]

Can you clarify how this change fixes the bug you are trying to fix (and what is
causing the bug in the first place)?

If GetTopWindowContainingPoint() ends up not being necessary, then yes please!
rm-rf code not used/necessary.

[afakhry, 2017/03/22 20:29:33]

Thanks.

GetTopWindowContaingPoint() on ARC++ devices return the ExoShellSurface window
rather than the window that's the owner widget of the window controller.
Resulting in returning early here
https://cs.chromium.org/chromium/src/ui/views/controls/menu/menu_controller.c...
without showing the sibling window.

More details are in this comment on the bug:
https://bugs.chromium.org/p/chromium/issues/detail?id=594439#c28

+  return root_window->GetEventHandlerForPoint(local_point);
 }
 
 int ScreenAsh::GetNumDisplays() const {
   return GetDisplayManager()->GetNumDisplays();
 }
 
 const std::vector<display::Display>& ScreenAsh::GetAllDisplays() const {
   return GetDisplayManager()->active_display_list();
 }
 
@@ skipping 71 matching lines @@
 }
 
 // static
 void ScreenAsh::CreateScreenForShutdown() {
   delete screen_for_shutdown;
   screen_for_shutdown = new ScreenForShutdown(display::Screen::GetScreen());
   display::Screen::SetScreenInstance(screen_for_shutdown);
 }
 
 }  // namespace ash