Add a workaround for crbug.com/139556.

Add a workaround for crbug.com/139556.

* Switch to the next IME when Shift+Alt+Enter (or Space) are pressed and then Enter (or Space) is released. Since most of CJK IMEs use either Enter or Space as a "commit" key, this should work fine for such IME users.
* The workaround might not be good enough for Cangjie/Quick IME users since the IME also uses [0-9] keys for committing a string.

We might have to add additional workaround for switching from a keyboard layout to an IME, but I believe this CL would be a good enough as an initial trial.

BUG=139556
TEST=added some new ash_unittests. also manually checked that the key repeat suppression change by mtomasz is still working fine.


Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=166868

[Yusuke Sato, 2012-11-09 01:13:14]

nona, let me add some workarounds for 139556. The current behavior is too
frustrating to use.....

[Seigo Nonaka, 2012-11-09 03:39:24]

LGTM

[Yusuke Sato, 2012-11-09 03:58:36]

+derat for owners review.

[Daniel Erat, 2012-11-09 04:57:43]

lgtm

[commit-bot: I haz the power, 2012-11-09 05:04:59]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/yusukes@chromium.org/11364168/1004

[commit-bot: I haz the power, 2012-11-09 06:58:14]

Change committed as 166868