Implement <appview>

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 39 matching lines @@
       "blessed_extension",
       "unblessed_extension",
       "content_script",
       "web_page",
       "blessed_web_page"
     ],
     "matches": [
       "http://*/*", "https://*/*", "chrome-extension://*/*", "file://*/*"
     ]
   },
+  "appViewInternal": {
+    "internal": true,
+    "channel": "dev",
+    "contexts": ["blessed_extension", "unblessed_extension"]
+  },
   "app.window": {
     "channel": "stable",
     "contexts": ["blessed_extension"],
     "extension_types": ["platform_app"],
     "noparent": true
   },
   "app.currentWindowInternal": {
     "noparent": true,
     "internal": true,
     "channel": "stable",
@@ skipping 692 matching lines @@
     "internal": true,
     "channel": "stable",
     "dependencies": ["permission:webview"],
     "contexts": ["blessed_extension"]
   },
   "windows": {
     "dependencies": ["api:tabs"],
     "contexts": ["blessed_extension"]
   }
 }