Yes, you are right. The focus should only show when search box is empty.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d00bd6d038486e505272d1abb50757d75edb0740

commit d00bd6d038486e505272d1abb50757d75edb0740
Author: Weidong Guo <weidongg@chromium.org>
Date: Wed Aug 09 22:51:14 2017

Avoid focus highlight in opened search box

Changes:
Avoid setting search box selected when search box has focus and it has
text query.

BUG= 753855 

Change-Id: Icba53d570f32c7994fb49ee29120f79a0094dd99
Reviewed-on: https://chromium-review.googlesource.com/609091
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Weidong Guo <weidongg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#493165}
[modify] https://crrev.com/d00bd6d038486e505272d1abb50757d75edb0740/ui/app_list/views/search_box_view.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/2c254ca03bc1fdbe8ffdf9c002a8a72777119113

commit 2c254ca03bc1fdbe8ffdf9c002a8a72777119113
Author: Maajid <maajid@chromium.org>
Date: Fri Aug 11 00:57:55 2017

Avoid focus highlight in opened search box

Changes:
Avoid setting search box selected when search box has focus and it has
text query.

BUG= 753855 
TBR=weidongg@chromium.org

(cherry picked from commit d00bd6d038486e505272d1abb50757d75edb0740)

Change-Id: Icba53d570f32c7994fb49ee29120f79a0094dd99
Reviewed-on: https://chromium-review.googlesource.com/609091
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Weidong Guo <weidongg@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#493165}
Reviewed-on: https://chromium-review.googlesource.com/611296
Reviewed-by: Vadim Tryshev <vadimt@chromium.org>
Cr-Commit-Position: refs/branch-heads/3163@{#480}
Cr-Branched-From: ff259bab28b35d242e10186cd63af7ed404fae0d-refs/heads/master@{#488528}
[modify] https://crrev.com/2c254ca03bc1fdbe8ffdf9c002a8a72777119113/ui/app_list/views/search_box_view.cc