GitLab

This CL simplifies how DriveAppRegistry stores App info.
Main purpose is to add |all_apps_|, the explicit list of
all application currently registered.

BUG=332014

Review URL: https://codereview.chromium.org/125813002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@243504 0039d316-1c4b-4281-b951-d872f2087c98