[Extensions Bindings] Introduce BindingAccessChecker

extensions/renderer/binding_access_checker.h

Index: extensions/renderer/binding_access_checker.h
diff --git a/extensions/renderer/binding_access_checker.h b/extensions/renderer/binding_access_checker.h
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+// Copyright 2017 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 EXTENSIONS_RENDERER_BINDING_ACCESS_CHECKER_H_
+#define EXTENSIONS_RENDERER_BINDING_ACCESS_CHECKER_H_
+
+#include <string>
+
+#include "base/callback.h"
+#include "base/macros.h"
+#include "v8/include/v8.h"
+
+namespace extensions {
+
+// A helper class to handle access-checking API features.
+class BindingAccessChecker {
+ public:
+  // The callback for determining if a given API feature (specified by |name|)
+  // is available in the given context.
+  using AvailabilityCallback =
+      base::Callback<bool(v8::Local<v8::Context>, const std::string& name)>;
+
+  BindingAccessChecker(const AvailabilityCallback& is_available);
+  ~BindingAccessChecker();
+
+  // Returns true if the feature specified by |full_name| is available to the
+  // given |context|.
+  bool HasAccess(v8::Local<v8::Context> context,
+                 const std::string& full_name) const;
+
+  // Same as HasAccess(), but throws an exception in the |context| if it doesn't
+  // have access.
+  bool HasAccessOrThrowError(v8::Local<v8::Context> context,
+                             const std::string& full_name) const;
+
+ private:
+  AvailabilityCallback is_available_;
+
+  DISALLOW_COPY_AND_ASSIGN(BindingAccessChecker);
+};
+
+}  // namespace extensions
+
+#endif  // EXTENSIONS_RENDERER_BINDING_ACCESS_CHECKER_H_