For unit tests, track additions to AtExitManager and warn.

base/at_exit.cc

Index: base/at_exit.cc
diff --git a/base/at_exit.cc b/base/at_exit.cc
index 0fba355698fbebc643fd3225d1323ec64964eb7d..5423ede8c127b3571145c3932240448dd6aa0a1b 100644
--- a/base/at_exit.cc
+++ b/base/at_exit.cc
@@ -1,4 +1,4 @@
-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
@@ -79,4 +79,13 @@ AtExitManager::AtExitManager(bool shadow) : next_manager_(g_top_manager) {
   g_top_manager = this;
 }
 
+// static
+AtExitManager* AtExitManager::current() {
+  return g_top_manager;
+}
+
+size_t AtExitManager::CallbackStackSize() const {
+  return stack_.size();
+}
+
 }  // namespace base