Turn on Commands Extension API for stable.

BUG=27702
TEST=See test plan for Commands API.

Review URL: https://chromiumcodereview.appspot.com/11411298

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@170622 0039d316-1c4b-4281-b951-d872f2087c98

chrome/common/extensions/api/_manifest_features.json

@@ -72,7 +72,7 @@
     "extension_types": ["extension", "packaged_app"]
   },
   "commands": {
-    "channel": "beta",
+    "channel": "stable",
     "extension_types": ["extension", "packaged_app", "platform_app"],
     "min_manifest_version": 2
   },