Fix null pointer dereference in PLSA's scrollbarStyleSource.

Fix null pointer dereference in PLSA's scrollbarStyleSource.

The scroller inside the alt-text shadow tree created by HTMLImageFallbackHelper
was trying to read scrollbar styles from the <img> element, which had no
LayoutObject because it was styled with "display: contents".

BUG=697247
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Review-Url: https://codereview.chromium.org/2734993002
Cr-Commit-Position: refs/heads/master@{#455148}
Committed: https://chromium.googlesource.com/chromium/src/+/d23ef9b37d71d31b82613f8ddb8da614cd54c665

[skobes, 2017-03-06 22:21:12]

Description was changed from

==========
Fix null pointer dereference in PLSA's scrollbarStyleSource.

The scroller inside the alt-text shadow tree created by HTMLImageFallbackHelper
was trying to read scrollbar styles from the <img> element, which had no
LayoutObject because it was styled with "display: contents".

BUG=697247
==========

to

==========
Fix null pointer dereference in PLSA's scrollbarStyleSource.

The scroller inside the alt-text shadow tree created by HTMLImageFallbackHelper
was trying to read scrollbar styles from the <img> element, which had no
LayoutObject because it was styled with "display: contents".

BUG=697247
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
==========

[skobes, 2017-03-06 22:21:31]

The CQ bit was checked by skobes@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2017-03-06 22:22:25]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-03-07 00:42:20]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-03-07 00:42:21]

Dry run: Try jobs failed on following builders:
  win_chromium_x64_rel_ng on master.tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_x64_...)

[skobes, 2017-03-07 00:44:01]

skobes@chromium.org changed reviewers:
+ szager@chromium.org

[szager1, 2017-03-07 00:55:44]

lgtm

[skobes, 2017-03-07 16:05:42]

The CQ bit was checked by skobes@chromium.org

[commit-bot: I haz the power, 2017-03-07 16:06:39]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-03-07 18:31:22]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1488902742100880, "parent_rev":
"d20a42b6f8b1f703717dac5c7936223ba129e1a3", "commit_rev":
"d23ef9b37d71d31b82613f8ddb8da614cd54c665"}

[commit-bot: I haz the power, 2017-03-07 18:32:02]

Description was changed from

==========
Fix null pointer dereference in PLSA's scrollbarStyleSource.

The scroller inside the alt-text shadow tree created by HTMLImageFallbackHelper
was trying to read scrollbar styles from the <img> element, which had no
LayoutObject because it was styled with "display: contents".

BUG=697247
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
==========

to

==========
Fix null pointer dereference in PLSA's scrollbarStyleSource.

The scroller inside the alt-text shadow tree created by HTMLImageFallbackHelper
was trying to read scrollbar styles from the <img> element, which had no
LayoutObject because it was styled with "display: contents".

BUG=697247
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Review-Url: https://codereview.chromium.org/2734993002
Cr-Commit-Position: refs/heads/master@{#455148}
Committed:
https://chromium.googlesource.com/chromium/src/+/d23ef9b37d71d31b82613f8ddb8d...
==========

[commit-bot: I haz the power, 2017-03-07 18:32:03]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/d23ef9b37d71d31b82613f8ddb8d...