Promote the downloads api to stable for M30!

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.
 
 {
   "activeTab": {
     "channel": "stable",
@@ skipping 170 matching lines @@
       "extension_types": ["extension", "packaged_app"]
     },
     {
       "channel": "stable",
       "extension_types": ["extension", "packaged_app"],
       // Legacy Browser Support (remove once this API hits stable).
       "whitelist": ["heildphpnddilhkemkielfhnkaagiabh"]
     }
   ],
   "downloads": {
-    "channel": "beta",
+    "channel": "stable",
     "extension_types": ["extension"]
   },
   "downloads.open": {
-    "channel": "beta",
+    "channel": "stable",
     "extension_types": ["extension"]
   },
   "downloads.shelf": {
-    "channel": "beta",
+    "channel": "stable",
     "extension_types": ["extension"]
   },
   "dial": {
     "channel": "stable",
     "extension_types": ["extension"],
     "whitelist": [
       "pkedcjkdefgpdelpbcmbmeomcjbeemfm",  // Trusted Tester
       "fmfcbgogabcbclcofgocippekhfcmgfj",  // Staging
       "hfaagokkkhdbgiakmmlclaapfelnkoah",  // Canary
       "F155646B5D1CA545F7E1E4E20D573DFDD44C2540",  // Trusted Tester (public)
@@ skipping 445 matching lines @@
   },
   "webRequestBlocking": {
     "channel": "stable",
     "extension_types": ["extension", "packaged_app"]
   },
   "webview": {
     "channel": "stable",
     "extension_types": ["platform_app"]
   }
 }