Reland 66791 (change was innocent)...

base/thread_restrictions.cc

Index: base/thread_restrictions.cc
===================================================================
--- base/thread_restrictions.cc	(revision 66806)
+++ base/thread_restrictions.cc	(working copy)
@@ -18,13 +18,16 @@
 LazyInstance<ThreadLocalBoolean, LeakyLazyInstanceTraits<ThreadLocalBoolean> >
     g_io_disallowed(LINKER_INITIALIZED);
 
+LazyInstance<ThreadLocalBoolean, LeakyLazyInstanceTraits<ThreadLocalBoolean> >
+    g_singleton_disallowed(LINKER_INITIALIZED);
+
 }  // anonymous namespace
 
 // static
 bool ThreadRestrictions::SetIOAllowed(bool allowed) {
-  bool previous_allowed = g_io_disallowed.Get().Get();
+  bool previous_disallowed = g_io_disallowed.Get().Get();
   g_io_disallowed.Get().Set(!allowed);
-  return !previous_allowed;
+  return !previous_disallowed;
 }
 
 // static
@@ -39,6 +42,22 @@
   }
 }
 
+bool ThreadRestrictions::SetSingletonAllowed(bool allowed) {
+  bool previous_disallowed = g_singleton_disallowed.Get().Get();
+  g_singleton_disallowed.Get().Set(!allowed);
+  return !previous_disallowed;
+}
+
+// static
+void ThreadRestrictions::AssertSingletonAllowed() {
+  if (g_singleton_disallowed.Get().Get()) {
+    LOG(FATAL) << "LazyInstance/Singleton is not allowed to be used on this "
+               << "thread.  Most likely it's because this thread is not "
+               << "joinable, so AtExitManager may have deleted the object "
+               << "on shutdown, leading to a potential shutdown crash.";
+  }
+}
+
 }  // namespace base
 
 #endif  // NDEBUG