MacViews: Fix MenuRunnerTests which fail with asan enabled.

ui/views/controls/menu/menu_controller.cc

Index: ui/views/controls/menu/menu_controller.cc
diff --git a/ui/views/controls/menu/menu_controller.cc b/ui/views/controls/menu/menu_controller.cc
index fcc41e8168a96ca30a5f3bf1225600be20e47fd6..c8166a5b590809021ddb264b99d3a362e6494844 100644
--- a/ui/views/controls/menu/menu_controller.cc
+++ b/ui/views/controls/menu/menu_controller.cc
@@ -1030,7 +1030,10 @@ ui::PostDispatchAction MenuController::OnWillDispatchKeyEvent(
   else
     OnKeyDown(key_code);
 
-  TerminateNestedMessageLoopIfNecessary();
+  // MenuController may have been deleted, so check for an active instance
+  // before accessing member variables.
+  if (GetActiveInstance())
+    TerminateNestedMessageLoopIfNecessary();
 
   return ui::POST_DISPATCH_NONE;
 }