Use interface associations to check function permissions.

This patch expands on r383543 to use correctly use the interface
associations parsed out of device descriptors to allow WebUSB
access controls to be specified at a function, rather than interface,
level.

BUG=492204
TBR=pfeldman@chromium.org

Review URL: https://codereview.chromium.org/1847183002

Cr-Commit-Position: refs/heads/master@{#384785}
20 files changed