Allow extensions of the ManifestParser outside of the content/ layer.

chrome/renderer/manifest/manifest_parser.h

+// Copyright 2015 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_RENDERER_MANIFEST_MANIFEST_PARSER_H_
+#define CHROME_RENDERER_MANIFEST_MANIFEST_PARSER_H_
+
+#include "content/public/renderer/manifest_parser.h"
+
+// ChromeManifestParser is an extension of the Manifest parser handling
+// properties specific to Chrome and unknown to the content/ layer.
+class ChromeManifestParser : public content::ManifestParser {
+ public:
+  ChromeManifestParser();
+  ~ChromeManifestParser() override;
+
+ protected:
+  void ParseExtensionPoint(const base::DictionaryValue& dictionary) override;
+
+ private:
+  // Parses the 'gcm_sender_id' field of the manifest.
+  // This is a proprietary extension of the Web Manifest specification.
+  // Returns the parsed string if any, a null string if the parsing failed.
+  base::NullableString16 ParseGCMSenderID(
+      const base::DictionaryValue& dictionary);
+
+  // Parses the 'gcm_user_visible_only' field of the manifest.
+  // This is a proprietary extension of the Web Manifest specification.
+  // Returns true iff the string could be parsed as the boolean true.
+  bool ParseGCMUserVisibleOnly(const base::DictionaryValue& dictionary);
+
+  DISALLOW_COPY_AND_ASSIGN(ChromeManifestParser);
+};
+
+#endif // CHROME_RENDERER_MANIFEST_MANIFEST_PARSER_H_