Implement Enterprise Key API.

chrome/common/extensions/api/_permission_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.
 
 {
   "activeTab": {
     "channel": "stable",
     "extension_types": ["extension", "packaged_app"],
     "min_manifest_version": 2
   },
@@ skipping 134 matching lines @@
     "channel": "stable",
     "extension_types": ["extension"],
     "whitelist": [
       "pkedcjkdefgpdelpbcmbmeomcjbeemfm",  // Trusted Tester
       "fmfcbgogabcbclcofgocippekhfcmgfj",  // Staging
       "hfaagokkkhdbgiakmmlclaapfelnkoah",  // Canary
       "F155646B5D1CA545F7E1E4E20D573DFDD44C2540",  // Trusted Tester (public)
       "16CA7A47AAE4BE49B1E75A6B960C3875E945B264"   // Release
     ]
   },
+  "enterprise.enterpriseKeyPrivate": {
+    "channel": "dev",
+    "extension_types": ["extension", "packaged_app"],
+    "whitelist": [
+    ]
+  },
   "experimental": {
     "channel": "stable",
     "extension_types": [
       "extension", "packaged_app", "hosted_app", "platform_app"
     ]
   },
   "fileBrowserHandler": {
     "channel": "stable",
     "extension_types": ["extension", "packaged_app", "platform_app"]
   },
@@ skipping 343 matching lines @@
   },
   "webRequestBlocking": {
     "channel": "stable",
     "extension_types": ["extension", "packaged_app"]
   },
   "webview": {
     "channel": "stable",
     "extension_types": ["platform_app"]
   }
 }