Update accept_return_character_ for synthetic events too.

Update accept_return_character_ for synthetic events too.

Tweak RenderWidgetHostViewAura RETURN key forwarding.
This is a followup fix for http://crrev.com/235194
That prevented forwarding CTRL+M as RETURN for Issue 315547.

This fixes RETURN handling for Win8 Metro Viewer processes.
Metro Viewer's synthetic events should be treated similarly.

BUG=321656, 315547
TEST=Win8 Metro Ash Chrome RETURN key should submit web forms.
TBR=nona@chromium.org,jochen@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=236478

[msw, 2013-11-20 23:42:44]

Hey Jochen and Nona, please take a look asap, thanks!

[msw, 2013-11-20 23:52:10]

Actually, I'm going to TBR this and put it in the CQ.
Hopefully we'll make tomorrow's canary and request merge.

[commit-bot: I haz the power, 2013-11-21 00:24:52]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/msw@chromium.org/79843002/1

[commit-bot: I haz the power, 2013-11-21 02:19:12]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/msw@chromium.org/79843002/1

[Seigo Nonaka, 2013-11-21 05:00:31]

lgtm

[commit-bot: I haz the power, 2013-11-21 09:25:22]

Change committed as 236478