query_parser is a components used by both history and bookmarks to avoid having
a cyclic dependencies between the two components. It only exports types used to
parse and normalize queries into the history search.

query_parser is not allowed to depend on content/, because it is used by iOS.
If dependences on content/ need to be added to query_parser, it will have to be
made into a layered component. See [1] for more information.

1: http://www.chromium.org/developers/design-documents/layered-components-design