Send one WebKeyboardEvent to the RenderWidget at a time. Move keyboard

Send one WebKeyboardEvent to the RenderWidget at a time.  Move keyboard
shortcut handling to the RenderWidgetHost.

R=jam@chromium.org

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=112160

[darin (slow to review), 2011-11-29 00:37:15]

Background:

I'm making this change to simplify event handling for the threaded compositor. 
The InputEventFilter used by the threaded compositor to route WebInputEvents to
the compositor's thread would require us to reproduce this shortcut handling
code on the compositor's thread.  It seems better to just delay sending key
events until we know whether the renderer wants them at all.

This is also a step toward always requiring an ACK before sending a
WebInputEvent to the RenderWidget.

NOTE: This change has no bearing on the Renderer.KeyboardQueueSize histogram. 
We were always appending to key_queue_ before, and only reducing its size when
we get an ACK.

[jam, 2011-11-29 02:57:54]

lgtm (caveat being that I'm not that familiar with the input forwarding code)

[commit-bot: I haz the power, 2011-11-29 18:19:11]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/darin@chromium.org/8727010/1

[commit-bot: I haz the power, 2011-11-29 20:25:13]

Try job failure for 8727010-1 (retry) (retry) on linux_rel for step
"interactive_ui_tests" (clobber build).
It's a second try, previously, step "compile" failed.
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=linux_rel&...

[commit-bot: I haz the power, 2011-11-30 05:19:03]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/darin@chromium.org/8727010/1

[commit-bot: I haz the power, 2011-11-30 08:17:58]

Change committed as 112160