Fix ScrollingCoordinator-related crash with page popups

Fix ScrollingCoordinator-related crash with page popups

Rev 444497 introduced a crash that can happen when popups are opened,
because in some cases they access the wrong compositor animation host
and timeline. This fixes the issue by ensure they always use those
resources on the top frame.

BUG=683282
Review-Url: https://codereview.chromium.org/2647963002
Cr-Commit-Position: refs/heads/master@{#445192}
(cherry picked from commit f15f669d84991252dd186c7093b885d7e909fad3)

Review-Url: https://codereview.chromium.org/2655743002 .
Cr-Commit-Position: refs/branch-heads/2987@{#63}
Cr-Branched-From: ad51088c0e8776e8dcd963dbe752c4035ba6dab6-refs/heads/master@{#444943}
Committed: https://chromium.googlesource.com/chromium/src/+/37f84209a3c632b8cd696c50eca923d533f0e1a8

[kenrb, 2017-01-24 18:30:03]

Description was changed from

==========
Fix ScrollingCoordinator-related crash with page popups

Rev 444497 introduced a crash that can happen when popups are opened,
because in some cases they access the wrong compositor animation host
and timeline. This fixes the issue by ensure they always use those
resources on the top frame.

BUG=683282

Review-Url: https://codereview.chromium.org/2647963002
Cr-Commit-Position: refs/heads/master@{#445192}
(cherry picked from commit f15f669d84991252dd186c7093b885d7e909fad3)
==========

to

==========
Fix ScrollingCoordinator-related crash with page popups

Rev 444497 introduced a crash that can happen when popups are opened,
because in some cases they access the wrong compositor animation host
and timeline. This fixes the issue by ensure they always use those
resources on the top frame.

BUG=683282

Review-Url: https://codereview.chromium.org/2647963002
Cr-Commit-Position: refs/heads/master@{#445192}
(cherry picked from commit f15f669d84991252dd186c7093b885d7e909fad3)

Review-Url: https://codereview.chromium.org/2655743002 .
Cr-Commit-Position: refs/branch-heads/2987@{#63}
Cr-Branched-From:
ad51088c0e8776e8dcd963dbe752c4035ba6dab6-refs/heads/master@{#444943}
Committed:
https://chromium.googlesource.com/chromium/src/+/37f84209a3c632b8cd696c50eca9...
==========

[kenrb, 2017-01-24 18:30:04]

Committed patchset #1 (id:1) manually as
37f84209a3c632b8cd696c50eca923d533f0e1a8.