RenderAccessibilityImpl::SnapshotAccessibilityTree should ensure layout clean.

RenderAccessibilityImpl::SnapshotAccessibilityTree should ensure layout clean.

BUG=642170
Committed: https://crrev.com/934c7bc4689a313f5e62123a61929755bac5ff6a
Cr-Commit-Position: refs/heads/master@{#415426}

[dmazzoni, 2016-08-29 23:06:29]

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

[dmazzoni, 2016-08-29 23:14:14]

dmazzoni@chromium.org changed reviewers:
+ aboxhall@chromium.org, nektar@chromium.org

[dmazzoni, 2016-08-29 23:14:15]

Alice and Nektarios, could you take a look at this?

As a reminder, RenderAccessibilityImpl::SnapshotAccessibilityTree is used
to implement Now On Tap on Android. We're seeing occasional crashes and a
very flaky clusterfuzz failure, and I've determined that the root cause
is that layout is not clean. Blink accessibility requires that layout is
clean and RenderAccessibilityImpl::SendPendingAccessibilityEvents() normally
enforces this before we serialize, but we weren't doing this from
SnapshotAccessibilityTree.

I haven't been able to write a test yet because it's tricky to actually
trigger a crash from layout not being clean, but I'd like to try this as a
speculative fix - hopefully we should be able to verify quickly that the
ClusterFuzz cases are fixed by this change.

Thanks!

[aboxhall, 2016-08-29 23:16:41]

lgtm

[nektarios, 2016-08-29 23:23:17]

lgtm

[commit-bot: I haz the power, 2016-08-30 02:18:45]

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, 2016-08-30 03:43:37]

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

[commit-bot: I haz the power, 2016-08-30 03:43:38]

Dry run: This issue passed the CQ dry run.

[dmazzoni, 2016-08-30 21:03:42]

The CQ bit was checked by dmazzoni@chromium.org

[commit-bot: I haz the power, 2016-08-30 21:04:27]

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, 2016-08-30 21:11:15]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-08-30 21:14:16]

Description was changed from

==========
RenderAccessibilityImpl::SnapshotAccessibilityTree should ensure layout clean.

BUG=642170
==========

to

==========
RenderAccessibilityImpl::SnapshotAccessibilityTree should ensure layout clean.

BUG=642170

Committed: https://crrev.com/934c7bc4689a313f5e62123a61929755bac5ff6a
Cr-Commit-Position: refs/heads/master@{#415426}
==========

[commit-bot: I haz the power, 2016-08-30 21:14:17]

Patchset 1 (id:??) landed as
https://crrev.com/934c7bc4689a313f5e62123a61929755bac5ff6a
Cr-Commit-Position: refs/heads/master@{#415426}