Merge list of orthogonal writing mode roots into depth-ordered layout list.

Merge list of orthogonal writing mode roots into depth-ordered layout list.

If we're going to perform a series of subtree layouts, rather than one layout
from LayoutView, and we at the same time have a list of orthogonal writing mode
roots that need to be laid out before their ancestors, we need to make sure
that subtrees are laid out in an overall tree depth ordered manner, or we risk
skipping layout of a subtree needing layout. That would cause trouble for the
column balancer (which examines the tree after layout and expects everything to
be laid out), and quite possibly other kinds of trouble elsewhere too.

BUG=680224
Review-Url: https://codereview.chromium.org/2635143003
Cr-Commit-Position: refs/heads/master@{#445497}
(cherry picked from commit 538d2655968dd8e6a8c3b8baec1b496dd4f74882)

Review-Url: https://codereview.chromium.org/2696713002 .
Cr-Commit-Position: refs/branch-heads/2987@{#486}
Cr-Branched-From: ad51088c0e8776e8dcd963dbe752c4035ba6dab6-refs/heads/master@{#444943}
Committed: https://chromium.googlesource.com/chromium/src/+/eb6e98df03a497ed99cc06e8741c18c12ae67572

[mstensho (USE GERRIT), 2017-02-13 20:30:21]

Description was changed from

==========
Merge list of orthogonal writing mode roots into depth-ordered layout list.

If we're going to perform a series of subtree layouts, rather than one layout
from LayoutView, and we at the same time have a list of orthogonal writing mode
roots that need to be laid out before their ancestors, we need to make sure
that subtrees are laid out in an overall tree depth ordered manner, or we risk
skipping layout of a subtree needing layout. That would cause trouble for the
column balancer (which examines the tree after layout and expects everything to
be laid out), and quite possibly other kinds of trouble elsewhere too.

BUG=680224

Review-Url: https://codereview.chromium.org/2635143003
Cr-Commit-Position: refs/heads/master@{#445497}
(cherry picked from commit 538d2655968dd8e6a8c3b8baec1b496dd4f74882)
==========

to

==========
Merge list of orthogonal writing mode roots into depth-ordered layout list.

If we're going to perform a series of subtree layouts, rather than one layout
from LayoutView, and we at the same time have a list of orthogonal writing mode
roots that need to be laid out before their ancestors, we need to make sure
that subtrees are laid out in an overall tree depth ordered manner, or we risk
skipping layout of a subtree needing layout. That would cause trouble for the
column balancer (which examines the tree after layout and expects everything to
be laid out), and quite possibly other kinds of trouble elsewhere too.

BUG=680224

Review-Url: https://codereview.chromium.org/2635143003
Cr-Commit-Position: refs/heads/master@{#445497}
(cherry picked from commit 538d2655968dd8e6a8c3b8baec1b496dd4f74882)

Review-Url: https://codereview.chromium.org/2696713002 .
Cr-Commit-Position: refs/branch-heads/2987@{#486}
Cr-Branched-From:
ad51088c0e8776e8dcd963dbe752c4035ba6dab6-refs/heads/master@{#444943}
Committed:
https://chromium.googlesource.com/chromium/src/+/eb6e98df03a497ed99cc06e8741c...
==========

[mstensho (USE GERRIT), 2017-02-13 20:30:22]

Committed patchset #1 (id:1) manually as
eb6e98df03a497ed99cc06e8741c18c12ae67572.