Move the chrome.automation API to dev channel.

chrome/common/extensions/api/_manifest_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 manifest keys implemented under src/chrome.
 // See extensions/common/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:
 //
@@ skipping 21 matching lines @@
   },
   "app.launch": {
     "channel": "stable",
     "extension_types": ["legacy_packaged_app", "hosted_app"]
   },
   "author": {
     "channel": "stable",
     "extension_types": "all"
   },
   "automation": {
-    "channel": "trunk",
+    "channel": "dev",
     "extension_types": ["extension", "legacy_packaged_app"]
   },
   "bluetooth": [{
     // Note: The "bluetooth" manifest permission is used by the
     // chrome.bluetooth, chrome.bluetoothSocket and chrome.bluetoothLowEnergy
     // APIs.
     "channel": "stable",
     "extension_types": ["platform_app"],
     "platforms": ["chromeos", "win", "mac"]
   }, {
@@ skipping 350 matching lines @@
   },
   "url_handlers": {
     "channel": "stable",
     "extension_types": ["platform_app"]
   },
   "version": {
     "channel": "stable",
     "extension_types": "all"
   }
 }