Add NULL check for renderBox::layer() on applying zoom level change

Add NULL check for renderBox::layer() on applying zoom level change

BUG=291293, 296164
R=tony@chromium.org
TEST="The repro step on crbug.com/296164 should not crash"

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=158238

[tzik, 2013-09-21 19:53:34]

PTL

[tony, 2013-09-23 16:38:14]

I think this fix is OK, but we need a layout test.  The example you uploaded
almost works and you can call eventSender.zoomPageIn() to simulate the page
zoom.  There are some similar tests in LayoutTests/fast/css/zoom-*.html (or you
can git grep for eventSender.zoomPage).

[tzik, 2013-09-23 19:33:57]

+test

[tzik, 2013-09-23 19:51:15]

On 2013/09/23 16:38:14, tony wrote:
> I think this fix is OK, but we need a layout test.  The example you uploaded
> almost works and you can call eventSender.zoomPageIn() to simulate the page
> zoom.  There are some similar tests in LayoutTests/fast/css/zoom-*.html (or
you
> can git grep for eventSender.zoomPage).

OK, I add a layout test for it.
The test cause crash on layout test, and it doesn't after my change.

Could you take another look?

[tony, 2013-09-23 21:37:53]

LGTM

https://codereview.chromium.org/23526081/diff/8001/LayoutTests/fast/css/zoom-...
File LayoutTests/fast/css/zoom-on-nested-scroll-crash-expected.txt (right):

https://codereview.chromium.org/23526081/diff/8001/LayoutTests/fast/css/zoom-...
LayoutTests/fast/css/zoom-on-nested-scroll-crash-expected.txt:3: Zooming in
(ctrl++) should not crash. The test is PASSED if it did not crash.
Grammar nit: The test PASSES if it does not crash.

[tzik, 2013-09-24 01:47:43]

Thanks!

https://codereview.chromium.org/23526081/diff/8001/LayoutTests/fast/css/zoom-...
File LayoutTests/fast/css/zoom-on-nested-scroll-crash-expected.txt (right):

https://codereview.chromium.org/23526081/diff/8001/LayoutTests/fast/css/zoom-...
LayoutTests/fast/css/zoom-on-nested-scroll-crash-expected.txt:3: Zooming in
(ctrl++) should not crash. The test is PASSED if it did not crash.
On 2013/09/23 21:37:53, tony wrote:
> Grammar nit: The test PASSES if it does not crash.

Done.

[commit-bot: I haz the power, 2013-09-24 01:48:23]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/tzik@chromium.org/23526081/20001

[commit-bot: I haz the power, 2013-09-24 04:37:44]

Change committed as 158238