cc: Prevent small scale factors (below 1) from being used or saved as the layer's rasterScale.

cc: Prevent small scale factors (below 1) from being used or saved as the layer's rasterScale.

When the scale is < 1, then we don't save anything. The first time we
see a scale >= 1, we will save it.

Tests:
cc_unittests:LayerTreeHostCommonTest.verifySmallContentsScale

BUG=159655
R=enne,jamesr

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=167040

[enne (OOO), 2012-11-09 23:15:57]

lgtm

[aelias_OOO_until_Jul13, 2012-11-09 23:19:04]

What's the motivation for this?  It would make us paint unnecessarily
expensively when zoomed out on a phone, and it would also degrade text quality.

[danakj, 2012-11-09 23:19:29]

On 2012/11/09 23:19:04, aelias wrote:
> What's the motivation for this?  It would make us paint unnecessarily
> expensively when zoomed out on a phone, and it would also degrade text
quality.

RAF animation, basically. See the linked bug.

[commit-bot: I haz the power, 2012-11-09 23:19:50]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/danakj@chromium.org/11377088/1

[danakj, 2012-11-09 23:20:10]

On 2012/11/09 23:19:29, danakj wrote:
> On 2012/11/09 23:19:04, aelias wrote:
> > What's the motivation for this?  It would make us paint unnecessarily
> > expensively when zoomed out on a phone, and it would also degrade text
> quality.
> 
> RAF animation, basically. See the linked bug.

PageScaleFactor can be < 1, that does not change. This only affects the
rasterScale, which is one component of the contentsScale.

[danakj, 2012-11-09 23:22:02]

On 2012/11/09 23:20:10, danakj wrote:
> On 2012/11/09 23:19:29, danakj wrote:
> > On 2012/11/09 23:19:04, aelias wrote:
> > > What's the motivation for this?  It would make us paint unnecessarily
> > > expensively when zoomed out on a phone, and it would also degrade text
> > quality.
> > 
> > RAF animation, basically. See the linked bug.
> 
> PageScaleFactor can be < 1, that does not change. This only affects the
> rasterScale, which is one component of the contentsScale.

I updated the test to demonstrate this.

[commit-bot: I haz the power, 2012-11-09 23:22:11]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/danakj@chromium.org/11377088/12001

[aelias_OOO_until_Jul13, 2012-11-09 23:24:33]

OK, thanks for the explanation, I commented before reading closely enough. 
LGTM.

[commit-bot: I haz the power, 2012-11-10 03:06:22]

Change committed as 167040