Fix event targeting for sub-windows of system modal windows in mus+ash.

services/ui/ws/modal_window_controller.cc

Index: services/ui/ws/modal_window_controller.cc
diff --git a/services/ui/ws/modal_window_controller.cc b/services/ui/ws/modal_window_controller.cc
index bb1c0bf135a439d22aecf86635158699c44e69a7..1a49731950d9ff38c331d187f168b035321ec840 100644
--- a/services/ui/ws/modal_window_controller.cc
+++ b/services/ui/ws/modal_window_controller.cc
@@ -78,7 +78,7 @@ bool ModalWindowController::IsWindowBlockedBy(
 
 bool ModalWindowController::IsWindowBlocked(const ServerWindow* window) const {
   DCHECK(window);
-  return GetActiveSystemModalWindow() || GetModalChildForWindowAncestor(window);
+  return GetTargetForWindow(window) != window;
 }
 
 const ServerWindow* ModalWindowController::GetTargetForWindow(
@@ -87,7 +87,8 @@ const ServerWindow* ModalWindowController::GetTargetForWindow(
   // children of their transient parent.
   ServerWindow* system_modal_window = GetActiveSystemModalWindow();
   if (system_modal_window)
-    return system_modal_window;
+    return system_modal_window->Contains(window) ? window : system_modal_window;
+
   return window ? GetWindowModalTargetForWindow(window) : nullptr;
 }