Revert "PackageInfo class incorrectly referenced as a struct."

This reverts commit b9b5d8c32e738d3607eec61e5d5bd95ca1521c2e.
Fixes for clang:
PackageInfo is a class, not a struct.
String16 is contained in the android namespace. Do not namespace prefix it
within the android namespace.
Explicitly specify which std classes are necessary to prevent ambiguous
type errors. (map, set)

Change-Id: I0d01477a976e770821ebae8847f8d11b132a15d6