Also, when you tap space when focus is on the expand arrow, the behavior looks weird: The ink drop will not disappear.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/c93e801b7d165f2ea18697caa2dd2ffe74c94a30

commit c93e801b7d165f2ea18697caa2dd2ffe74c94a30
Author: Weidong Guo <weidongg@chromium.org>
Date: Tue Jul 25 03:16:25 2017

Fix search box issue when expand arrow has focus

Changes:
1. Override OnKeyPressed function in ExpandArrowView to prevent SPACE
key being handled by parent view.
2. Avoid returning true for unhandled key event in
StartPageView::OnKeyPressed.

BUG= 747146 

Change-Id: Ie3a195b133ba57040299deb1bbe542ed80462e1c
Reviewed-on: https://chromium-review.googlesource.com/582235
Commit-Queue: Weidong Guo <weidongg@chromium.org>
Reviewed-by: Yury Khmel <khmel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#489207}
[modify] https://crrev.com/c93e801b7d165f2ea18697caa2dd2ffe74c94a30/ui/app_list/views/expand_arrow_view.cc
[modify] https://crrev.com/c93e801b7d165f2ea18697caa2dd2ffe74c94a30/ui/app_list/views/expand_arrow_view.h
[modify] https://crrev.com/c93e801b7d165f2ea18697caa2dd2ffe74c94a30/ui/app_list/views/start_page_view.cc

Your change meets the bar and is auto-approved for M61. Please go ahead and merge the CL to branch 3163 manually. Please contact milestone owner if you have questions.
Owners: amineer@(Android), cmasso@(iOS), ketakid @(ChromeOS), govind@(Desktop)

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/4c90190e8b252c3606131feabb64d50c1b20487e

commit 4c90190e8b252c3606131feabb64d50c1b20487e
Author: Maajid <maajid@chromium.org>
Date: Sat Jul 29 01:01:50 2017

Fix search box issue when expand arrow has focus

Changes:
1. Override OnKeyPressed function in ExpandArrowView to prevent SPACE
key being handled by parent view.
2. Avoid returning true for unhandled key event in
StartPageView::OnKeyPressed.

BUG= 747146 
TBR=weidongg@chromium.org

(cherry picked from commit c93e801b7d165f2ea18697caa2dd2ffe74c94a30)

Change-Id: Ie3a195b133ba57040299deb1bbe542ed80462e1c
Reviewed-on: https://chromium-review.googlesource.com/582235
Commit-Queue: Weidong Guo <weidongg@chromium.org>
Reviewed-by: Yury Khmel <khmel@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#489207}
Reviewed-on: https://chromium-review.googlesource.com/592707
Reviewed-by: Vadim Tryshev <vadimt@chromium.org>
Cr-Commit-Position: refs/branch-heads/3163@{#130}
Cr-Branched-From: ff259bab28b35d242e10186cd63af7ed404fae0d-refs/heads/master@{#488528}
[modify] https://crrev.com/4c90190e8b252c3606131feabb64d50c1b20487e/ui/app_list/views/expand_arrow_view.cc
[modify] https://crrev.com/4c90190e8b252c3606131feabb64d50c1b20487e/ui/app_list/views/expand_arrow_view.h
[modify] https://crrev.com/4c90190e8b252c3606131feabb64d50c1b20487e/ui/app_list/views/start_page_view.cc

Verified on Chrome OS 9765.13.0, 61.0.3163.20 (dev build).