Add blakeo@ and shend@ to OWNERS of ui/keyboard.

This CL also removes obsolete entries:
  - bshe@ (no longer working on VK)
  - bryeung@ and kevers@ (no longer in Chrome team)
  - sadrul@ (already the owner of the parent directory)

Bug: None
Change-Id: Ia49203ff7fd65a22fe1fa9aff0b38e8bf5257337
Reviewed-on: https://chromium-review.googlesource.com/1098433
Commit-Queue: Yuichiro Hanada <yhanada@chromium.org>
Reviewed-by: Darren Shen <shend@chromium.org>
Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Cr-Commit-Position: refs/heads/master@{#567217}

ui/keyboard/OWNERS

-sadrul@chromium.org
-wuyingbing@chromium.org
+blakeo@chromium.org
+shend@chromium.org
 shuchen@chromium.org
-bshe@chromium.org
+wuyingbing@chromium.org
 yhanada@chromium.org
 
-# Use the following owners only when the above owners are not available.
-kevers@chromium.org
-bryeung@chromium.org
-
 # COMPONENT: UI>Input>VirtualKeyboard