Move sockets manifest types to //extensions.

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.
 
 // See c/c/e/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 311 matching lines @@
   },
   "extension.onRequest": {
     "contexts": ["blessed_extension", "unblessed_extension", "content_script"]
   },
   "extension.sendNativeMessage": {
     "dependencies": ["permission:nativeMessaging"]
   },
   "extension.sendRequest": {
     "contexts": ["blessed_extension", "unblessed_extension", "content_script"]
   },
+  // 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"]
   },
   "fileBrowserHandler": {
     "platforms": ["chromeos"],
     "dependencies": ["permission:fileBrowserHandler"],
     "contexts": ["blessed_extension"]
   },
   "fileBrowserHandlerInternal": {
@@ skipping 448 matching lines @@
     "internal": true,
     "channel": "stable",
     "dependencies": ["permission:webview"],
     "contexts": ["blessed_extension"]
   },
   "windows": {
     "dependencies": ["api:tabs"],
     "contexts": ["blessed_extension"]
   }
 }