Enabling webview in app_shell.

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.
 
 // This features file defines extension APIs implemented under src/chrome.
 // See extensions/common/features/* to understand this file, in particular
 // feature.h, simple_feature.h, and base_feature_provider.h.
 //
 // Note that specifying "web_page", "blessed_web_page", or "all" as a context
 // type will require manually updating chrome/renderer/resources/dispatcher.cc.
@@ skipping 419 matching lines @@
     "contexts": ["blessed_extension"]
   },
   "gcdPrivate": {
     "dependencies": ["permission:gcdPrivate"],
     "contexts": ["blessed_extension"]
   },
   "gcm": {
     "dependencies": ["permission:gcm"],
     "contexts": ["blessed_extension"]
   },
-  "guestViewInternal": [{
-    "internal": true,
-    "channel": "stable",
-    "contexts": ["blessed_extension"]
-  }, {
-    // Component extensions can use the guestViewInternal API from iframes.
-    "location": "component",
-    "internal": true,
-    "dependencies": ["permission:webview"],
-    "contexts": ["unblessed_extension"]
-  }, {
-    "internal": true,
-    "channel": "trunk",
-    "contexts": ["webui"],
-    "matches": ["chrome://extensions-frame/*", "chrome://extensions/*"]
-  }],
   "hangoutsPrivate": {
     "channel": "stable",
     "contexts": ["blessed_extension"],
     "whitelist": [
       // http://crbug.com/309737
       "nckgahadagoaajjgafhacjanaoiihapd",
       "ljclpkphhpbpinifbeabbhlfddcpfdde",
       "ppleadejekpmccmnpjdimmlfljlkdfej",
       "eggnbpckecmjlblplehfpjjdhhidfdoj",
       "jfjjdfefebklmdbmenmlehlopoocnoeh",
@@ skipping 324 matching lines @@
     "internal": true,
     "channel": "stable",
     "dependencies": ["permission:webview"],
     "contexts": ["blessed_extension"]
   },
   "windows": {
     "dependencies": ["api:tabs"],
     "contexts": ["blessed_extension"]
   }
 }