Implement autosizing for <extensionoptions>

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 347 matching lines @@
     "dependencies": ["permission:nativeMessaging"]
   },
   "extension.sendRequest": {
     "contexts": ["blessed_extension", "unblessed_extension", "content_script"]
   },
   "extensionOptionsInternal": {
     "internal": true,
     "contexts": ["blessed_extension"],
     "dependencies": ["permission:embeddedExtensionOptions"]
   },
+  "extensionOptionsInternal.onSizeChanged": {

[not at google - send to devlin, 2014/07/30 17:44:57]

you shouldn't need to specify this? it should be covered by the
extensionOptionsInternal rule.

[ericzeng, 2014/07/30 23:29:26]

Forgot to remove it after rebasing

+    "internal": true,
+    "channel": "trunk",
+    "contexts": ["blessed_extension"],
+    "dependencies": ["permission:embeddedExtensionOptions"]
+  },
   // This is not a real API, only here for documentation purposes.
   // See http://crbug.com/275944 for background.
   "extensionsManifestTypes": {
     "internal": true,
     "channel": "stable",
     "contexts": ["blessed_extension"]
   },
   "feedbackPrivate": {
     "dependencies": ["permission:feedbackPrivate"],
     "contexts": ["blessed_extension"]
@@ skipping 393 matching lines @@
     "internal": true,
     "channel": "stable",
     "dependencies": ["permission:webview"],
     "contexts": ["blessed_extension"]
   },
   "windows": {
     "dependencies": ["api:tabs"],
     "contexts": ["blessed_extension"]
   }
 }