Enforce the 'requirements' field in manifests.

chrome/browser/extensions/requirements_provider_impl.h

+// Copyright (c) 2012 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 CHROME_BROWSER_EXTENSIONS_REQUIREMENTS_PROVIDER_IMPL_H_
+#define CHROME_BROWSER_EXTENSIONS_REQUIREMENTS_PROVIDER_IMPL_H_
+#pragma once
+
+#include "chrome/common/extensions/requirements_provider.h"
+
+namespace extensions {
+
+class RequirementsProviderImpl : public RequirementsProvider {
+ public:
+  RequirementsProviderImpl();
+
+  virtual bool Supports(const Manifest& manifest, string16* error);
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_REQUIREMENTS_PROVIDER_IMPL_H_