GitLab

Known caveat:
- Since GCM on Android only supports a single registration per native
  app, only a single web app can register at once, and even then only
  if they pass --disable-sync-gcm-in-order-to-try-push-api on the command
  line which disables Chrome Sync etc from receiving GCM messages.

Depends on https://codereview.chromium.org/316963003/

BUG=350384

Review URL: https://codereview.chromium.org/314293006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@276795 0039d316-1c4b-4281-b951-d872f2087c98