Correct the squashing origin w.r.t. the transformed ancestor to take into account rounding to integ…

Correct the squashing origin w.r.t. the transformed ancestor to take into account rounding to integer
offsets.

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=176457

[chrishtr, 2014-06-18 19:24:11]

This subtlety doesn't typically show up visually, since the value is only used
for computing repaint rects, which cc
expands.

But it seems clearly correct to make this change. I found it
while investigating another bug.
In addition, the offsetFromRenderer and subpixelAccumulation
of the actual squashed layers depend on this same squash layerorigin.

[Ian Vollick, 2014-06-18 20:08:14]

On 2014/06/18 19:24:11, chrishtr wrote:
> This subtlety doesn't typically show up visually, since the value is only used
> for computing repaint rects, which cc
> expands.
> 
> But it seems clearly correct to make this change. I found it
> while investigating another bug.
> In addition, the offsetFromRenderer and subpixelAccumulation
> of the actual squashed layers depend on this same squash layerorigin.

I agree. To use the location of the squashing layer without taking into account
the integer conversions that are done to it later does seem wrong.

This lgtm.

[chrishtr, 2014-06-18 20:11:12]

The CQ bit was checked by chrishtr@chromium.org

[commit-bot: I haz the power, 2014-06-18 20:11:48]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/chrishtr@chromium.org/345613004/1

[commit-bot: I haz the power, 2014-06-18 22:18:20]

Change committed as 176457