Enable EditableCombobox on Windows.

Tested on Windows and once again it worked seamlessly. The only change
needed was in a unit test to capture the fact that ctrl+right behaves
differently on Windows (it moves to the beginning of the next word
instead of the end of the current one).

Turns out the extra challenge of propagating the keys to the
TextInputClient was only a problem on Mac.

Bug: 923660
Change-Id: I58dfe93dbf282ddfd69ca9d2cf53847d5420a8dc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1513272
Commit-Queue: Edin Kadric <edinkadric@google.com>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#640086}
2 files changed