Filter unnecessary GestureFlingCancel events.

Filter unnecessary GestureFlingCancel events.

The WebKit compositor delegates GestureFlingCancel events to the
main thread if there is not already a fling in progress. This reduces
the scrolling responsiveness of webpages while they are loading.

Tested via unit test and use of a slow loading test page.

BUG=137555
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=150463

[rjkroege, 2012-08-07 16:54:53]

sadrul@ Can you have a look-over?

[sadrul, 2012-08-07 17:13:17]

LGTM with some comments

http://codereview.chromium.org/10855027/diff/1/content/browser/renderer_host/...
File content/browser/renderer_host/render_widget_host_impl.cc (right):

http://codereview.chromium.org/10855027/diff/1/content/browser/renderer_host/...
content/browser/renderer_host/render_widget_host_impl.cc:495: fling_in_progress_
= false;
Should this be set to false only when is_loading is set?

http://codereview.chromium.org/10855027/diff/1/content/browser/renderer_host/...
content/browser/renderer_host/render_widget_host_impl.cc:840: fling_in_progress_
= false;
Perhaps we can call ShouldDiscardFlingCancelEvent here? (and DCHECK in
ShouldDiscardFlingCancelEvent to make sure it always receives a fling-cancel
event)

http://codereview.chromium.org/10855027/diff/1/content/browser/renderer_host/...
content/browser/renderer_host/render_widget_host_impl.cc:1537: return false;
no braces here

[rjkroege, 2012-08-07 21:00:29]

sky@ for owner please?

http://codereview.chromium.org/10855027/diff/1/content/browser/renderer_host/...
File content/browser/renderer_host/render_widget_host_impl.cc (right):

http://codereview.chromium.org/10855027/diff/1/content/browser/renderer_host/...
content/browser/renderer_host/render_widget_host_impl.cc:495: fling_in_progress_
= false;
On 2012/08/07 17:13:17, sadrul wrote:
> Should this be set to false only when is_loading is set?

I don't think so. Otherwise, we could send unnecessary fling cancel events when
the page is busy.

http://codereview.chromium.org/10855027/diff/1/content/browser/renderer_host/...
content/browser/renderer_host/render_widget_host_impl.cc:840: fling_in_progress_
= false;
On 2012/08/07 17:13:17, sadrul wrote:
> Perhaps we can call ShouldDiscardFlingCancelEvent here? (and DCHECK in
> ShouldDiscardFlingCancelEvent to make sure it always receives a fling-cancel
> event)

Reasonable. Done.

Done.

http://codereview.chromium.org/10855027/diff/1/content/browser/renderer_host/...
content/browser/renderer_host/render_widget_host_impl.cc:1537: return false;
On 2012/08/07 17:13:17, sadrul wrote:
> no braces here

Done.

[sky, 2012-08-07 22:32:02]

LGTM

[commit-bot: I haz the power, 2012-08-07 22:46:39]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/rjkroege@chromium.org/10855027/3002

[commit-bot: I haz the power, 2012-08-08 00:07:34]

Change committed as 150463