Fix "modal isn't modal in multi displays" issue

ash/wm/system_modal_container_layout_manager.h

Index: ash/wm/system_modal_container_layout_manager.h
diff --git a/ash/wm/system_modal_container_layout_manager.h b/ash/wm/system_modal_container_layout_manager.h
index be35747b0be07be361b48e863ed53e2cf0274acc..81e2fe1de121daf3118355b8130d1efda4a6ac65 100644
--- a/ash/wm/system_modal_container_layout_manager.h
+++ b/ash/wm/system_modal_container_layout_manager.h
@@ -54,8 +54,9 @@ class ASH_EXPORT SystemModalContainerLayoutManager
   // Overridden from keyboard::KeyboardControllerObserver:
   void OnKeyboardBoundsChanging(const gfx::Rect& new_bounds) override;
 
-  // Can a given |window| receive and handle input events?
-  bool CanWindowReceiveEvents(aura::Window* window);
+  // True if the window is either contained by the top most modal window,
+  // or contained by its transient children.
+  bool IsPartOfActiveModalWindow(aura::Window* window);
 
   // Activates next modal window if any. Returns false if there
   // are no more modal windows in this layout manager.