Add the "file_handlers" manifest key for platform apps to replace "intents".

This patch just adds a synonym for the "intents" functionality, but the
eventual intention is to remove the intents code from extensions altogether.

R=benwells@chromium.org,jhawkins@chromium.org


Review URL: https://chromiumcodereview.appspot.com/11360026

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@165628 0039d316-1c4b-4281-b951-d872f2087c98
15 files changed