GitLab

Also replace NULL with nullptr throughout FocusManager and
FocusSearch.

Bug: 764918
Change-Id: Ic90607c470130ac53375b26e601c1226c34a501a
Reviewed-on: https://chromium-review.googlesource.com/1024990Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Dominic Mazzoni <dmazzoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#552907}