[SharedArrayBuffer] Add "AllowShared" extended attribute, used for WebGL

third_party/WebKit/Source/bindings/core/v8/V8Binding.h

 /*
 * Copyright (C) 2009 Google Inc. All rights reserved.
 * Copyright (C) 2012 Ericsson AB. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
@@ skipping 29 matching lines @@
 #include "bindings/core/v8/ScriptState.h"
 #include "bindings/core/v8/ScriptValue.h"
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "bindings/core/v8/V8BindingMacros.h"
 #include "bindings/core/v8/V8PerIsolateData.h"
 #include "bindings/core/v8/V8ScriptRunner.h"
 #include "bindings/core/v8/V8StringResource.h"
 #include "bindings/core/v8/V8ThrowException.h"
 #include "bindings/core/v8/V8ValueCache.h"
 #include "core/CoreExport.h"
+#include "core/dom/MaybeShared.h"
 #include "core/dom/NotShared.h"
 #include "platform/heap/Handle.h"
 #include "platform/wtf/text/AtomicString.h"
 #include "platform/wtf/text/StringView.h"
 #include "v8/include/v8.h"
 
 namespace blink {
 
 class DOMWindow;
 class EventListener;
@@ skipping 1129 matching lines @@
   DOMTypedArray* dom_typed_array =
       V8TypeOf<DOMTypedArray>::Type::toImplWithTypeCheck(isolate, value);
   if (dom_typed_array && dom_typed_array->IsShared()) {
     exception_state.ThrowTypeError(
         "The provided ArrayBufferView value must not be shared.");
     return NotSharedType();
   }
   return NotSharedType(dom_typed_array);
 }
 
+// Wrap a typed array value in MaybeShared<>, to signify that it may be backed
+// by a SharedArrayBuffer.
+template <typename MaybeSharedType>
+MaybeSharedType ToMaybeShared(v8::Isolate* isolate,
+                              v8::Local<v8::Value> value,
+                              ExceptionState& exception_state) {
+  using DOMTypedArray = typename MaybeSharedType::TypedArrayType;
+  DOMTypedArray* dom_typed_array =
+      V8TypeOf<DOMTypedArray>::Type::toImplWithTypeCheck(isolate, value);
+  return MaybeSharedType(dom_typed_array);
+}
+
 }  // namespace blink
 
 #endif  // V8Binding_h