Add ExtendSelectionAndDelete handler in WebPlugin

Add ExtendSelectionAndDelete handler in WebPlugin

This ExtendSelectionAndDelete message should be routed to plugin for
supporting IME on browser_plugin etc.

This is in addition to
https://codereview.chromium.org/102963005
(Add supportsInputMethod() interface for WebPlugin)
to support IME in WebPlugin.

This corresponds to nona's review comment in
https://codereview.chromium.org/103403006/#msg14

BUG=235573
TEST=will be covered in content_browsertest
R=tkent@chromium.org

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=163839

[kochi, 2013-12-12 09:57:26]

tkent-san,

Could you review this?
Thanks,

[tkent, 2013-12-12 23:34:06]

lgtm

> This ExtendSelectionAndDelte message should be routed to plugin for 

Delte -> Delete

[kochi, 2013-12-13 01:18:46]

On 2013/12/12 23:34:06, tkent wrote:
> lgtm
> 
> > This ExtendSelectionAndDelte message should be routed to plugin for 
> 
> Delte -> Delete

Thanks, typo fixed.

[commit-bot: I haz the power, 2013-12-13 01:19:00]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/kochi@chromium.org/100193005/1

[commit-bot: I haz the power, 2013-12-13 03:50:25]

Retried try job too often on win_layout for step(s) webkit_lint
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=win_layout...

[kochi, 2013-12-13 03:59:59]

Committed patchset #1 manually as r163839 (presubmit successful).