Add WorkerDocumentSet::ContainsExternalRenderer(int worker_process_id)

It will be called to checks to see if the document set contains any documents which is associated with other renderer process than worker_process_id.

BUG=327256

Review URL: https://codereview.chromium.org/178473016

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@254928 0039d316-1c4b-4281-b951-d872f2087c98
2 files changed