Implement cross-origin attributes using access check interceptors.

third_party/WebKit/Source/bindings/core/v8/V8CrossOriginSetterInfo.h

+// Copyright 2016 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.
+
+#ifndef V8CrossOriginSetterInfo_h
+#define V8CrossOriginSetterInfo_h
+
+#include "wtf/Allocator.h"
+#include <v8.h>
+
+namespace blink {
+
+// Simple adapter that is used in place of v8::PropertyCallbackInfo for setters
+// that are accessible cross-origin. This is needed because a named access check
+// interceptor takes a v8::PropertyCallbackInfo<v8::Value> argument, while a
+// normal setter interceptor takes a v8::PropertyCallbackInfo<void> argument.

[haraken, 2016/12/08 08:21:02]

Hmm, this looks nasty. Can we fix it in a follow-up CL?

[dcheng, 2016/12/08 09:04:10]

I don't see an easy way to fix it without changing v8. I'm not actually sure why
the access check interceptor has a v8::Value argument: 99.9% of the time, it
seems like the return value is just going to be the input value, so v8 can do
that itself. Maybe +jochen has some history on this.

(I've fixed this comment to fix some incorrect terminology as well)

+//
+// Since the generated bindings only care about two fields (the isolate and the
+// holder), the generated bindings just substitutes this for the normal
+// v8::PropertyCallbackInfo argument, so the same generated function can be used
+// to handle intercepted cross-origin sets and normal sets.
+class V8CrossOriginSetterInfo {
+  STACK_ALLOCATED();
+
+ public:
+  V8CrossOriginSetterInfo(v8::Isolate* isolate, v8::Local<v8::Object> holder)
+      : m_isolate(isolate), m_holder(holder) {}
+
+  v8::Isolate* GetIsolate() const { return m_isolate; }
+  v8::Local<v8::Object> Holder() const { return m_holder; }
+
+ private:
+  v8::Isolate* m_isolate;
+  v8::Local<v8::Object> m_holder;
+};
+
+}  // namespace blink
+
+#endif  // V8CrossOriginSetterInfo_h