Identity API: enable chrome.identity in dev channel

chrome.identity is replacing chrome.experimental.identity. The
experimental version will be deleted as soon as some legacy users
switch to chrome.identity.

BUG=124493

Review URL: https://chromiumcodereview.appspot.com/15904006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@202020 0039d316-1c4b-4281-b951-d872f2087c98

chrome/common/extensions/api/_permission_features.json

@@ -176,7 +176,7 @@
     ]
   },
   "identity": {
-    "channel": "trunk",
+    "channel": "dev",
     "extension_types": ["extension", "platform_app"]
   },
   "enterprise.platformKeysPrivate": {