The new class hierarchy encapsulates the packageUriResolver and
packages parameters that were previously used in the
ContextManagerCallback API. In a future CL, I intend to use it more
extensively within ContextManagerImpl in order to make the algorithm
for choosing contexts more declarative.
R=brianwilkerson@google.com
Review URL: https://codereview.chromium.org//1258473003 .
Paul Berry
7fb62213cf