Enforce restricted precision of the Battery Status API level attribute

Enforce restricted precision of the Battery Status API level attribute

Make sure to provide the level attribute with no more than 2 digits of
precision. This is to avoid the possibility of fingerprinting and to
provide consistent behavior across platforms.

BUG=507326
Committed: https://crrev.com/637776d1183dd286f040349341e1881023851ef9
git-svn-id: svn://svn.chromium.org/blink/trunk@199517 bbb929c8-8fbe-4397-9dbb-9b2b20218538

[timvolodine, 2015-07-10 12:08:35]

timvolodine@chromium.org changed reviewers:
+ battre@chromium.org

[timvolodine, 2015-07-14 11:14:23]

battre@: does this patch look ok to you?

[battre, 2015-07-14 11:53:46]

LGTM from my perspective but I have no experience with layout tests. Would be
good to have somebody else review the CL.

Thanks!

Best regards,
Dominic

[timvolodine, 2015-07-14 17:39:02]

timvolodine@chromium.org changed reviewers:
+ mlamouri@chromium.org

[timvolodine, 2015-07-14 17:39:02]

thanks Dominic,

adding mlamouri@ to take a look as well.

[mlamouri (slow - plz ping), 2015-07-16 10:47:39]

I think it would be better to enforce that the backend sends only 1% granularity
battery level updates instead of rounding in Blink. I would consider rounding as
a last resort. Should we maybe assert if it's not rounded?

[timvolodine, 2015-07-24 15:29:23]

On 2015/07/16 10:47:39, Mounir Lamouri wrote:
> I think it would be better to enforce that the backend sends only 1%
granularity
> battery level updates instead of rounding in Blink. I would consider rounding
as
> a last resort. Should we maybe assert if it's not rounded?

I don't think delegating this to platform backends is a good solution. Some
platforms are implemented by different people and it's hard to enforce this kind
of constraint on them. Also by doing it centrally in blink we can enforce a
consistent and guaranteed behavior there. Assert would be hard to test since
hardware is not guaranteed to provide fractional values all the time..

[battre, 2015-07-24 15:33:48]

On 2015/07/24 15:29:23, timvolodine wrote:
> On 2015/07/16 10:47:39, Mounir Lamouri wrote:
> > I think it would be better to enforce that the backend sends only 1%
> granularity
> > battery level updates instead of rounding in Blink. I would consider
rounding
> as
> > a last resort. Should we maybe assert if it's not rounded?
> 
> I don't think delegating this to platform backends is a good solution. Some
> platforms are implemented by different people and it's hard to enforce this
kind
> of constraint on them. Also by doing it centrally in blink we can enforce a
> consistent and guaranteed behavior there. Assert would be hard to test since
> hardware is not guaranteed to provide fractional values all the time..

+1

[timvolodine, 2015-07-27 15:19:42]

On 2015/07/24 15:33:48, battre wrote:
> On 2015/07/24 15:29:23, timvolodine wrote:
> > On 2015/07/16 10:47:39, Mounir Lamouri wrote:
> > > I think it would be better to enforce that the backend sends only 1%
> > granularity
> > > battery level updates instead of rounding in Blink. I would consider
> rounding
> > as
> > > a last resort. Should we maybe assert if it's not rounded?
> > 
> > I don't think delegating this to platform backends is a good solution. Some
> > platforms are implemented by different people and it's hard to enforce this
> kind
> > of constraint on them. Also by doing it centrally in blink we can enforce a
> > consistent and guaranteed behavior there. Assert would be hard to test since
> > hardware is not guaranteed to provide fractional values all the time..
> 
> +1

I am going to land this now because it fixes a potential privacy issue.

[timvolodine, 2015-07-27 15:20:40]

The CQ bit was checked by timvolodine@chromium.org

[commit-bot: I haz the power, 2015-07-27 15:20:45]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1229143006/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1229143006/20001

[commit-bot: I haz the power, 2015-07-27 16:30:41]

Committed patchset #2 (id:20001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=199517

[mlamouri (slow - plz ping), 2015-08-05 08:55:50]

post-fact lgtm, I was on holidays, sorry.

[commit-bot: I haz the power, 2015-09-23 11:48:49]

Patchset 2 (id:??) landed as
https://crrev.com/637776d1183dd286f040349341e1881023851ef9