fileSystemProvider: First cut at implementing fileSystemProvider API

Implement fileSystemProvider.mount() that does not do anything meaningful
yet. The purpose of this patch is to add boilerplate files so adding new
code is easier.

Design doc of the API: http://goo.gl/lLXJYQ

BUG=248427
TEST=none
R=benwells@chromium.org, kinuko@chromium.org
TBR=thestig@chromium.org
# TBR thestig@ for chrome/renderer/resources/renderer_resources.grd

Review URL: https://codereview.chromium.org/50703013

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@233799 0039d316-1c4b-4281-b951-d872f2087c98
22 files changed