Revert of Revert cursor changes to RenderWidgetHostViewAura.

content/browser/renderer_host/render_widget_host_view_aura.cc

Index: content/browser/renderer_host/render_widget_host_view_aura.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_aura.cc b/content/browser/renderer_host/render_widget_host_view_aura.cc
index f978056c130659c4d8c3fa595dd391c8dea1960b..fd50cf54b0e64c354ee490b338f5a2f6b720747a 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura.cc
@@ -2435,11 +2435,11 @@
 
   gfx::Point cursor_screen_point = screen->GetCursorScreenPoint();
 
-#if !defined(OS_CHROMEOS)
+#if defined(OS_WIN)
   // Ignore cursor update messages if the window under the cursor is not us.
   aura::Window* window_at_screen_point = screen->GetWindowAtScreenPoint(
       cursor_screen_point);
-#if defined(OS_WIN)
+
   // On Windows we may fail to retrieve the aura Window at the current cursor
   // position. This is because the WindowFromPoint API may return the legacy
   // window which is not associated with an aura Window. In this case we need
@@ -2455,12 +2455,15 @@
     window_at_screen_point = screen_win->GetNativeWindowFromHWND(
         hwnd_at_point);
   }
-#endif  // defined(OS_WIN)
+
   if (!window_at_screen_point ||
       (window_at_screen_point->GetRootWindow() != root_window)) {
     return;
   }
-#endif  // !defined(OS_CHROMEOS)
+#elif !defined(OS_CHROMEOS)
+  if (!screen->IsWindowUnderCursor(window_))
+    return;
+#endif
 
   gfx::Point root_window_point = cursor_screen_point;
   aura::client::ScreenPositionClient* screen_position_client =