New UMA stats for stacking container opt-in measurements.

New UMA stats for stacking container opt-in measurements.

Along with https://codereview.chromium.org/23874003/, this
adds Renderer.CompositedScrolling UMA histogram.

This records the total number of RenderLayers that are scrollable
areas, need to become stacking containers, and will use composited
scrolling.

Each of the buckets should be recorded at most once per
RenderLayer. The ratio between these stats should give
us an idea of how effective stacking containers are at
allowing scrollable divs to become composited.

BUG=

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=157227

[hartmanng, 2013-09-03 17:33:42]

Ian, please take a look.

These are the new UMA stats for the old comp-scroll path (stacking containers),
along with the histogram definitions here:
https://codereview.chromium.org/23874003.

These can start gathering data right away, and then the other half of the stats
(ie, the part for the new compositorDrivenAcceleratedScrolling path) can be
added as part of https://codereview.chromium.org/20103002/ or as a follow-up
patch.

[Ian Vollick, 2013-09-03 18:28:07]

lgtm with nit.

https://codereview.chromium.org/23455031/diff/1/Source/core/rendering/RenderL...
File Source/core/rendering/RenderLayer.cpp (right):

https://codereview.chromium.org/23455031/diff/1/Source/core/rendering/RenderL...
Source/core/rendering/RenderLayer.cpp:6206: }
This should happen inside the previous 'if', I think. if (frameView->add...) {
compositor()->...; <new code>; }

[hartmanng, 2013-09-03 21:26:56]

Ian, PTAL. This patch combines the histograms into one, as it will make it
easier to compare the ratios. I've also updated
https://codereview.chromium.org/23874003/, but not published yet, in case of
naming nits.

https://codereview.chromium.org/23455031/diff/1/Source/core/rendering/RenderL...
File Source/core/rendering/RenderLayer.cpp (right):

https://codereview.chromium.org/23455031/diff/1/Source/core/rendering/RenderL...
Source/core/rendering/RenderLayer.cpp:6206: }
On 2013/09/03 18:28:07, Ian Vollick wrote:
> This should happen inside the previous 'if', I think. if (frameView->add...) {
> compositor()->...; <new code>; }

Done.

[Ian Vollick, 2013-09-03 22:44:52]

On 2013/09/03 21:26:56, hartmanng wrote:
> Ian, PTAL. This patch combines the histograms into one, as it will make it
> easier to compare the ratios. I've also updated
> https://codereview.chromium.org/23874003/, but not published yet, in case of
> naming nits.
> 
>
https://codereview.chromium.org/23455031/diff/1/Source/core/rendering/RenderL...
> File Source/core/rendering/RenderLayer.cpp (right):
> 
>
https://codereview.chromium.org/23455031/diff/1/Source/core/rendering/RenderL...
> Source/core/rendering/RenderLayer.cpp:6206: }
> On 2013/09/03 18:28:07, Ian Vollick wrote:
> > This should happen inside the previous 'if', I think. if (frameView->add...)
{
> > compositor()->...; <new code>; }
> 
> Done.

slgtm

[Alexei Svitkine (slow), 2013-09-04 15:21:19]

lgtm with a nit

https://codereview.chromium.org/23455031/diff/16001/Source/core/rendering/Ren...
File Source/core/rendering/RenderLayer.cpp (right):

https://codereview.chromium.org/23455031/diff/16001/Source/core/rendering/Ren...
Source/core/rendering/RenderLayer.cpp:2105:
HistogramSupport::histogramEnumeration("Renderer.CompositedScrolling",
NeedsToBeStackingContainerBucket, 3);
Nit: Instead of hardcoding 3 for the last param at all the callsites, add it to
the enum - naming it something like CompositedScrollingHistogramMax.

[hartmanng, 2013-09-04 15:48:56]

thanks!

https://codereview.chromium.org/23455031/diff/16001/Source/core/rendering/Ren...
File Source/core/rendering/RenderLayer.cpp (right):

https://codereview.chromium.org/23455031/diff/16001/Source/core/rendering/Ren...
Source/core/rendering/RenderLayer.cpp:2105:
HistogramSupport::histogramEnumeration("Renderer.CompositedScrolling",
NeedsToBeStackingContainerBucket, 3);
On 2013/09/04 15:21:19, Alexei Svitkine wrote:
> Nit: Instead of hardcoding 3 for the last param at all the callsites, add it
to
> the enum - naming it something like CompositedScrollingHistogramMax.
> 

Done.

[commit-bot: I haz the power, 2013-09-04 15:49:10]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/hartmanng@chromium.org/23455031/22001

[commit-bot: I haz the power, 2013-09-04 18:00:53]

Change committed as 157227