Never throttle unconsumed touchmove acks

Never throttle unconsumed touchmove acks

Throttling unconsumed touchmove's (particularly the first touchmove) when the
main thread is heavy blocks accelerated scrolling.  This is most evident during
page load, when the accelerated path is the only viable path for fluid touch
interaction.  Address this by completely disabling RenderWidget ack throttling
for unconsumed touchmoves.

BUG=366765
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=266114

[jdduke (slow), 2014-04-24 19:11:39]

brianderson@: PTAL per offline discussion.  I think it's OK to treat touchmove's
special here, as they're probably the only events that have "follow-up" created
events that need to be dispatched to the renderer.

piman@: OWNER review.

[jdduke (slow), 2014-04-24 19:12:59]

https://codereview.chromium.org/252443006/diff/20001/content/renderer/render_...
File content/renderer/render_widget.cc (right):

https://codereview.chromium.org/252443006/diff/20001/content/renderer/render_...
content/renderer/render_widget.cc:1062: ack_result ==
INPUT_EVENT_ACK_STATE_CONSUMED);
Alternatively, we can move the |CONSUMED| check below and to line 1087, and
never throttle acks for any unconsumed type.

[piman, 2014-04-24 19:30:36]

lgtm

[jdduke (slow), 2014-04-24 21:24:59]

The CQ bit was checked by jdduke@chromium.org

[commit-bot: I haz the power, 2014-04-24 21:44:14]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/jdduke@chromium.org/252443006/20001

[commit-bot: I haz the power, 2014-04-25 03:17:23]

Change committed as 266114