Temporary workaround for flashing buts on Mac

Temporary workaround for flashing buts on Mac

Do not re-set the root layer for the ui::Compositor when suspending the
browser compositor view. Prior to moving the ui::Compositor to use the
scheduler, this would prevent frames from appearing. Now it causes blank
flashes.

There are still blue (debug) flashes when returning from fullscreen and
when the GPU process is killed. These still need to be fixed.

BUG=454682
Committed: https://crrev.com/afebf76e26c5cecb3fa043c410f64ed96243a09e
Cr-Commit-Position: refs/heads/master@{#314632}

[ccameron, 2015-02-04 20:05:22]

ccameron@chromium.org changed reviewers:
+ weiliangc@chromium.org

[ccameron, 2015-02-04 20:05:23]

This will ensure that Mac Canary/Dev isn't in too-terrible shape while I sort
out a better solution (I'd wait longer, but with sheriffing, I don't think I'll
get to it in the next day).

[weiliangc, 2015-02-04 20:14:33]

On 2015/02/04 at 20:05:23, ccameron wrote:
> This will ensure that Mac Canary/Dev isn't in too-terrible shape while I sort
out a better solution (I'd wait longer, but with sheriffing, I don't think I'll
get to it in the next day).

LGTM and thanks!

[ccameron, 2015-02-04 20:21:14]

Thanks for the quick review!

[ccameron, 2015-02-04 20:21:17]

The CQ bit was checked by ccameron@chromium.org

[commit-bot: I haz the power, 2015-02-04 20:22:01]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/903543002/1

[commit-bot: I haz the power, 2015-02-04 21:09:25]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-04 21:10:23]

Patchset 1 (id:??) landed as
https://crrev.com/afebf76e26c5cecb3fa043c410f64ed96243a09e
Cr-Commit-Position: refs/heads/master@{#314632}