[VK] Don't disable keyboard in IME tray due to temporary hide.

When we use the IME menu tray in laptop mode, we temporarily enable the
accessibility virtual keyboard. When the keyboard is dismissed, we
disable the accessibility keyboard again. However, when we change the
keyboard between docked and floating mode, the keyboard has to hide
first before showing again. This causes the accessibility keyboard to be
disabled and the keyboard doesn't show up again.

We fix this by adding an additional parameter to OnKeyboardHidden
which indicates whether the keyboard is hidden temporarily.

TBR=sky@chromium.org

Bug: 858953
Change-Id: I162917e5e32e6081be49127a3e7e9cf5fbeeb11c
Reviewed-on: https://chromium-review.googlesource.com/1137803
Commit-Queue: Darren Shen <shend@chromium.org>
Reviewed-by: Blake O'Hare <blakeo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#576400}
7 files changed