Implement API features for the Extension API feature system

chrome/common/extensions/api/_api_features.json

+// 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.
+
+{
+  "bookmarks": {
+    "channel": "stable",
+    "dependencies": ["permission:bookmarks"],
+    "contexts": ["blessed_extension"]
+  },
+  "webstore": {
+    // Hosted apps can use the webstore API from within a blessed context.
+    "channel": "stable",
+    "extension_types": ["hosted_app"],
+    "contexts": ["blessed_extension", "web_page"],
+    // Any webpage can use the webstore API.
+    "matches": [ "http://*/*", "https://*/*" ]
+  }
+}