Merge to M52: Fix a bug with the Chrome legacy window at times becoming a top level window with a n…

Merge to M52: Fix a bug with the Chrome legacy window at times becoming a top level window with a non functional button in the taskbar.

This bug typically occurs if the legacy window stays around after it is
removed from the original root window.

It looks like a recent change (https://codereview.chromium.org/1996163002)
which ensures that the legacy window is always created exacerbates this
problem by creating the legacy windows early and some of them stay around
after a tab switch. Typical cases include opening a pdf file in chrome
which causes at least two RWVHA instances to be active at any given point
and the legacy window which belongs to the original instance becomes a
button on the taskbar when the tab is switched.

Fix is to never reparent to the desktop window and instead always reparent
to the hidden window.

BUG=616410
Review-Url: https://codereview.chromium.org/2031213002
Cr-Commit-Position: refs/heads/master@{#397790}
(cherry picked from commit b35c046639c244df4a954a791e24cfe7d5270daa)

Committed: https://chromium.googlesource.com/chromium/src/+/2529de3d35849bb1e6a4d9b8ec80ca41c9004f3d

[dmazzoni, 2016-06-07 23:38:56]

Description was changed from

==========
Merge to M52: Fix a bug with the Chrome legacy window at times becoming a top
level window with a non functional button in the taskbar.

This bug typically occurs if the legacy window stays around after it is
removed from the original root window.

It looks like a recent change (https://codereview.chromium.org/1996163002)
which ensures that the legacy window is always created exacerbates this
problem by creating the legacy windows early and some of them stay around
after a tab switch. Typical cases include opening a pdf file in chrome
which causes at least two RWVHA instances to be active at any given point
and the legacy window which belongs to the original instance becomes a
button on the taskbar when the tab is switched.

Fix is to never reparent to the desktop window and instead always reparent
to the hidden window.

BUG=616410

Review-Url: https://codereview.chromium.org/2031213002
Cr-Commit-Position: refs/heads/master@{#397790}
(cherry picked from commit b35c046639c244df4a954a791e24cfe7d5270daa)
==========

to

==========
Merge to M52: Fix a bug with the Chrome legacy window at times becoming a top
level window with a non functional button in the taskbar.

This bug typically occurs if the legacy window stays around after it is
removed from the original root window.

It looks like a recent change (https://codereview.chromium.org/1996163002)
which ensures that the legacy window is always created exacerbates this
problem by creating the legacy windows early and some of them stay around
after a tab switch. Typical cases include opening a pdf file in chrome
which causes at least two RWVHA instances to be active at any given point
and the legacy window which belongs to the original instance becomes a
button on the taskbar when the tab is switched.

Fix is to never reparent to the desktop window and instead always reparent
to the hidden window.

BUG=616410

Review-Url: https://codereview.chromium.org/2031213002
Cr-Commit-Position: refs/heads/master@{#397790}
(cherry picked from commit b35c046639c244df4a954a791e24cfe7d5270daa)

Committed:
https://chromium.googlesource.com/chromium/src/+/2529de3d35849bb1e6a4d9b8ec80...
==========

[dmazzoni, 2016-06-07 23:38:59]

Committed patchset #1 (id:1) manually as
2529de3d35849bb1e6a4d9b8ec80ca41c9004f3d.