Implement DriveAppRegistry::UninstallApp() and GetAppList().

BUG=324166

First Commit: https://src.chromium.org/viewvc/chrome?view=rev&revision=244182
Reverted: https://src.chromium.org/viewvc/chrome?view=rev&revision=244189

R=hashimoto@chromium.org

Review URL: https://codereview.chromium.org/133123004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@244824 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 244824