GitLab

This CL hooks up the toolbar forward and backward buttons in grouped mode to
change the search timeframe for week and month queries.

BUG=589357
TBR=dbeam@chromium.org
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2481693002
Cr-Commit-Position: refs/heads/master@{#435547}