Disable background mode for v2 packaged apps.

There will be system tray support for these coming out in future. In the meantime we don't want apps to start relying on the background mode.

BUG=163770


Review URL: https://chromiumcodereview.appspot.com/11421193

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@170844 0039d316-1c4b-4281-b951-d872f2087c98

chrome/common/extensions/api/_permission_features.json

@@ -32,7 +32,7 @@
   "background": {
     "channel": "stable",
     "extension_types": [
-      "extension", "packaged_app", "hosted_app", "platform_app"
+      "extension", "packaged_app", "hosted_app"
     ]
   },
   "bluetooth": {