Reland r65996. Disallows Singletons on non-joinable thread.

base/lazy_instance.h

Index: base/lazy_instance.h
diff --git a/base/lazy_instance.h b/base/lazy_instance.h
index ebf1e73024cb5d2ba1455fe8161d89b06a7cc39e..f8d59873f297484a120ebf927fcd2bfeb48bdb79 100644
--- a/base/lazy_instance.h
+++ b/base/lazy_instance.h
@@ -36,14 +36,19 @@
 #define BASE_LAZY_INSTANCE_H_
 #pragma once
 
+#include <new>  // For placement new.
+
 #include "base/atomicops.h"
 #include "base/basictypes.h"
 #include "base/third_party/dynamic_annotations/dynamic_annotations.h"
+#include "base/thread_restrictions.h"
 
 namespace base {
 
 template <typename Type>
 struct DefaultLazyInstanceTraits {
+  static const bool kAllowedToAccessOnNonjoinableThread = false;
+
   static Type* New(void* instance) {
     // Use placement new to initialize our instance in our preallocated space.
     // The parenthesis is very important here to force POD type initialization.
@@ -57,6 +62,8 @@ struct DefaultLazyInstanceTraits {
 
 template <typename Type>
 struct LeakyLazyInstanceTraits {
+  static const bool kAllowedToAccessOnNonjoinableThread = true;
+
   static Type* New(void* instance) {
     return DefaultLazyInstanceTraits<Type>::New(instance);
   }
@@ -112,6 +119,9 @@ class LazyInstance : public LazyInstanceHelper {
   }
 
   Type* Pointer() {
+    if (!Traits::kAllowedToAccessOnNonjoinableThread)
+      base::ThreadRestrictions::AssertSingletonAllowed();
+
     // We will hopefully have fast access when the instance is already created.
     if ((base::subtle::NoBarrier_Load(&state_) != STATE_CREATED) &&
         NeedsInstance()) {
@@ -126,7 +136,6 @@ class LazyInstance : public LazyInstanceHelper {
     // and CompleteInstance(...) happens before "return instance_" below.
     // See the corresponding HAPPENS_BEFORE in CompleteInstance(...).
     ANNOTATE_HAPPENS_AFTER(&state_);
-
     return instance_;
   }