Promote chrome.app.window alwaysOnTop property to stable unwhitelisted

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.
 
 // See c/c/e/features/* to understand this file, in particular feature.h,
 // simple_feature.h, and base_feature_provider.h.
 
 // To add a new whitelisted ID, SHA-1 it and force it to uppercase. In Bash:
 //
 // $ echo -n "aaaabbbbccccddddeeeeffffgggghhhh" | \
@@ skipping 22 matching lines @@
   },
   "adview": {
     "channel": "dev",
     "extension_types": ["platform_app"]
   },
   "alarms": {
     "channel": "stable",
     "extension_types": ["extension", "legacy_packaged_app", "platform_app"],
     "min_manifest_version": 2
   },
-  "alwaysOnTopWindows": [
-    {
-      "channel": "dev",
-      "extension_types": ["platform_app"]
-    },
-    {
-      "channel": "stable",
-      "extension_types": ["platform_app"],
-      "whitelist": [
-        "0F42756099D914A026DADFA182871C015735DD95",
-        "2D22CDB6583FD0A13758AEBE8B15E45208B4E9A7"
-      ]
-    }
-  ],
+  "alwaysOnTopWindows": {
+    "channel": "stable",
+    "extension_types": ["platform_app"]
+  },
   "audio": [
     {
       "channel": "dev",
       "extension_types": ["platform_app"]
     },
     {
       "channel": "stable",
       "extension_types": ["platform_app"],
       "whitelist": [
         "8C3741E3AF0B93B6E8E0DDD499BB0B74839EA578",
@@ skipping 888 matching lines @@
     // 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
     ]
   }]
 }