The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a9a6608f362a5c14d05edc292c2ffcf40152f1d3

commit a9a6608f362a5c14d05edc292c2ffcf40152f1d3
Author: Ryan Landay <rlanday@chromium.org>
Date: Fri Oct 20 00:55:43 2017

Make DPAD_CENTER key events show soft input on keyup, not keydown

When a native Android EditText widget is focused, the DPAD_CENTER keyboard event
(e.g. from the center button on the Nexus Player remote) causes the on-screen
keyboard to show on keyup. Currently in WebView, we're showing the keyboard on
keydown, and then the on-screen keyboard is receiving the keyup event. In
Android Oreo, the keyboard was rewritten and when the new keyboard receives this
keyup event, it types the character selected by default on the keyboard (usually
'1').

The fix is to not show the keyboard until keyup, to match the behavior of
Android EditText. Despite no longer doing anything in response to the keydown
event, we still want to make the event prevent default instead of passing it to
the web app, since passing it to the web app would cause compatibility problems.
E.g. the Facebook app for Android TV would blur the input element in response to
the keydown immediately after the keyboard is opened (which causes the keyboard
to close again).

Bug:  776591 
Change-Id: Icf893f8d2ef27825d78d2bc264575a62b0e77648
Reviewed-on: https://chromium-review.googlesource.com/729281
Reviewed-by: Alexandre Elias <aelias@chromium.org>
Reviewed-by: Changwan Ryu <changwan@chromium.org>
Commit-Queue: Ryan Landay <rlanday@chromium.org>
Cr-Commit-Position: refs/heads/master@{#510277}
[modify] https://crrev.com/a9a6608f362a5c14d05edc292c2ffcf40152f1d3/content/public/android/javatests/src/org/chromium/content/browser/input/ImeTest.java
[modify] https://crrev.com/a9a6608f362a5c14d05edc292c2ffcf40152f1d3/content/renderer/input/render_widget_input_handler.cc