Move DispatchKeyEvent to InputMethodWinBase

The DispatchKeyEvent in InputMethodWinBaseIMM32 does not have any code
special to IMM32, so I move it to InputMethodWinBase, which can be
shared by both InputMethodWinBaseIMM32 and InputMethodWinBaseTSF.

This CL does not have any new behavior change. This DispatchKeyEvent
works when TSF is enabled, but I will try to use TSF API to replace
PeekMessage API in the following CLs.


Bug: 657623
Change-Id: I0b03f7b393660676ff26df1a9bdbfbbd43dc6a45
Reviewed-on: https://chromium-review.googlesource.com/1173336
Commit-Queue: Lan Wei <lanwei@chromium.org>
Reviewed-by: Shu Chen <shuchen@chromium.org>
Reviewed-by: Yohei Yukawa <yukawa@chromium.org>
Cr-Commit-Position: refs/heads/master@{#583423}
8 files changed