Remove the webview API whitelist (just the GAIA component extension).

extensions/common/api/_permission_features.json

 // Copyright 2014 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 permissions for extension APIs implemented
 // under src/extensions.
 
 // See extensions/common/features/* to understand this file, in particular
 // feature.h, simple_feature.h, and base_feature_provider.h.
 
@@ skipping 103 matching lines @@
       "1C93BD3CF875F4A73C0B2A163BB8FBDA8B8B3D80",  // http://crbug.com/387169
       "A3BC37E2148AC4E99BE4B16AF9D42DD1E592BBBE",  // http://crbug.com/387169
       "E703483CEF33DEC18B4B6DD84B5C776FB9182BDB",  // http://crbug.com/387169
       "307E96539209F95A1A8740C713E6998A73657D96",  // http://crbug.com/387169
       "4F25792AF1AA7483936DE29C07806F203C7170A0",  // http://crbug.com/407693
       "BD8781D757D830FC2E85470A1B6E8A718B7EE0D9",  // http://crbug.com/407693
       "4AC2B6C63C6480D150DFDA13E4A5956EB1D0DDBB",  // http://crbug.com/407693
       "81986D4F846CEDDDB962643FA501D1780DD441BB"   // http://crbug.com/407693
     ]
   },
-  "declarativeWebRequest": [
-    {
+  "declarativeWebRequest": {
       "channel": "beta",
       "extension_types": ["extension", "legacy_packaged_app"]
-    }
-  ],
+  },
   "dns": [
     {
       "channel": "dev",
       "extension_types": ["extension", "platform_app"]
     },
     {
       "channel": "stable",
       "extension_types": ["extension", "platform_app"],
       "whitelist": [
         "7AE714FFD394E073F0294CFA134C9F91DB5FBAA4",  // CCD Development
@@ skipping 178 matching lines @@
         "09FDCB5851B8F3378DB630D06E316076E89C95A6",
         "A434B90223C3C52F2B69DB494736B63C612C774D"
       ]
     }
   ],
   "vpnProvider": {
     "channel": "dev",
     "extension_types": ["extension", "platform_app"],
     "platforms": ["chromeos"]
   },
-  "webview": [
-    {
-      "channel": "stable",
-      "extension_types": ["platform_app"]
-    },
-    {
-      // General support for webview in component extensions still in progress.
-      // Only allowed for whitelisted extensions until all the caveats are
-      // addressed. Tracked in crbug/285151.
-      "channel": "stable",
-      "extension_types": ["extension"],
-      "location": "component",
-      "whitelist": [
-        "D519188F86D9ACCEE0412007B227D9936EB9676B"  // GAIA Component Extension
-      ]
-    }
-  ],
-  "webRequest": [
-    {
+  "webview": {
+    "channel": "stable",
+    "extension_types": ["platform_app"]
+  },
+  "webRequest": {
     "channel": "stable",
     "extension_types": ["extension", "legacy_packaged_app"]
-     }
-  ],
-  "webRequestBlocking": [
-    {
+   },
+  "webRequestBlocking": {
     "channel": "stable",
     "extension_types": ["extension", "legacy_packaged_app"]
-    }
-  ]
+  }
 }