mus: Fix handled status in UI event ack, add MessageLoop::NestingObserver

base/message_loop/message_loop_test.h

Index: base/message_loop/message_loop_test.h
diff --git a/base/message_loop/message_loop_test.h b/base/message_loop/message_loop_test.h
index 3d9889cd58dd88f2dcda9a16fed2378b16ed458f..a0f1a96ea7d7846a027fab1e45de0d2ea38522fb 100644
--- a/base/message_loop/message_loop_test.h
+++ b/base/message_loop/message_loop_test.h
@@ -28,6 +28,7 @@ void RunTest_PostDelayedTask_SharedTimer(MessagePumpFactory factory);
 void RunTest_EnsureDeletion(MessagePumpFactory factory);
 void RunTest_EnsureDeletion_Chain(MessagePumpFactory factory);
 void RunTest_Nesting(MessagePumpFactory factory);
+void RunTest_NestingObserver(MessagePumpFactory factory);
 void RunTest_RecursiveDenial1(MessagePumpFactory factory);
 void RunTest_RecursiveDenial3(MessagePumpFactory factory);
 void RunTest_RecursiveSupport1(MessagePumpFactory factory);
@@ -84,6 +85,9 @@ void RunTest_RecursivePosts(MessagePumpFactory factory);
   TEST(MessageLoopTestType##id, Nesting) { \
     base::test::RunTest_Nesting(factory); \
   } \
+  TEST(MessageLoopTestType##id, NestingObserver) { \
+    base::test::RunTest_NestingObserver(factory); \
+  } \
   TEST(MessageLoopTestType##id, RecursiveDenial1) { \
     base::test::RunTest_RecursiveDenial1(factory); \
   } \