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

chrome/renderer/manifest/manifest_parser.cc

+// 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.
+
+#include "chrome/renderer/manifest/manifest_parser.h"
+
+ChromeManifestParser::ChromeManifestParser()
+    : ManifestParser() {}
+
+ChromeManifestParser::~ChromeManifestParser() {}
+
+void ChromeManifestParser::ParseExtensionPoint(
+    const base::DictionaryValue& dictionary) {
+  manifest_.gcm_sender_id = ParseGCMSenderID(dictionary);
+  manifest_.gcm_user_visible_only = ParseGCMUserVisibleOnly(dictionary);
+}
+
+base::NullableString16 ChromeManifestParser::ParseGCMSenderID(
+    const base::DictionaryValue& dictionary)  {
+  return ParseString(dictionary, "gcm_sender_id", Trim);
+}
+
+bool ChromeManifestParser::ParseGCMUserVisibleOnly(
+    const base::DictionaryValue& dictionary) {
+  return ParseBoolean(dictionary, "gcm_user_visible_only", false);
+}