Annotate ScriptWrappable-embedding singletons.

third_party/WebKit/Source/wtf/StdLibExtras.h

Index: third_party/WebKit/Source/wtf/StdLibExtras.h
diff --git a/third_party/WebKit/Source/wtf/StdLibExtras.h b/third_party/WebKit/Source/wtf/StdLibExtras.h
index 26ba1d8d02958298aacfc73daea5743ccbbce201..e88a4f6267e287ff7ddba3296ef6f65142d62d3f 100644
--- a/third_party/WebKit/Source/wtf/StdLibExtras.h
+++ b/third_party/WebKit/Source/wtf/StdLibExtras.h
@@ -26,12 +26,13 @@
 #ifndef WTF_StdLibExtras_h
 #define WTF_StdLibExtras_h
 
+#include <cstddef>
 #include "base/numerics/safe_conversions.h"
+#include "wtf/Allocator.h"
 #include "wtf/Assertions.h"
 #include "wtf/CPU.h"
 #include "wtf/LeakAnnotations.h"
 #include "wtf/TypeTraits.h"
-#include <cstddef>
 
 #if DCHECK_IS_ON()
 #include "wtf/Noncopyable.h"
@@ -112,13 +113,24 @@ class StaticLocalWrapper<T, true> {
 // LEAK_SANITIZER_REGISTER_STATIC_LOCAL() use, it taking care of the grungy
 // details.
 //
-#define DEFINE_STATIC_LOCAL(Type, Name, Arguments)                   \
-  DEFINE_STATIC_LOCAL_CHECK_THREADSAFE_ACCESS(Name);                 \
-  using WrappedTypeFor##Name = StaticLocalWrapper<Type>::WrapType;   \
-  static WrappedTypeFor##Name* WrappedInstanceFor##Name =            \
-      LEAK_SANITIZER_REGISTER_STATIC_LOCAL(                          \
-          WrappedTypeFor##Name, new WrappedTypeFor##Name Arguments); \
-  Type& Name = StaticLocalWrapper<Type>::unwrap(WrappedInstanceFor##Name);
+
+#define DEFINE_STATIC_LOCAL(Type, Name, Arguments)                      \
+  STATIC_ALLOCATED_SINGLETON()                                          \
+  static StaticLocalWrapper<Type>::WrapType* WrappedInstanceFor##Name = \
+      LEAK_SANITIZER_REGISTER_STATIC_LOCAL(                             \
+          StaticLocalWrapper<Type>::WrapType,                           \
+          new StaticLocalWrapper<Type>::WrapType Arguments);            \
+  DEFINE_STATIC_LOCAL_CHECK_THREADSAFE_ACCESS(Name);                    \
+  Type& Name = StaticLocalWrapper<Type>::unwrap(WrappedInstanceFor##Name)
+
+// Static local singletons that embed ScriptWrappable-derived objects are
+// problematic (see issue 688569). The clang GC plugin issues warnings
+// when encountering such singletons. If you cannot avoid introducing
+// the static local and can prove that the ScriptWrappable reference is
+// safe, you may use ALLOW_UNSAFE_SINGLETON() to disable the clang GC
+// plugin check. See issue 688569 for more details.
+//
+#define ALLOW_UNSAFE_SINGLETON() GC_PLUGIN_IGNORE("crbug.com/688569")
 
 // Use this to declare and define a static local pointer to a ref-counted object
 // so that it is leaked so that the object's destructors are not called at